83 Xj750 maxim starting problem

I Just recently bought a 1983 xj750 maxim. It has a problem where it only starts when starting fluid is sprayed in to the air pod filters. It will stay on afterwards only if I keep revving it . If I let go of the gas it will slowly shut off.

Here are details of the bike.

1.It does not have the Original air box one of the previous owners added pod filters. (I doubt they ever rejetted the carbs)
2.The guy I bought it from said he rebuilt the carburetors, the bowls do get gas and the needles do move up and down. butterflies open and close ( They don't close perfectly they lay in an angle leaving a small gap on top and bottom)
3. Two of the intake boots have cracks near nipples, I don't know if they go all trough into the inside. (Haven't taken the boots of because I need to go buy some Hex keys and I don't really want to ruin the seals if I don't have too) The boots are hard but still playable. All the nipples are covered by a rubber cap
4. The vacuum hose of the gas tank is attached to the nipple of the inlet of the 3rd carburetor (counting from the left hand side) I'm not sure if that is how it supposed to be or what. (I'm not familiar with this model bike or working on bikes for that matter)

I really would like to get this bike back in tip top shape but then again I don't want to be throwing money at trying to fix something that is not broken (opening up the carburetors to inspect for a problem only to find out it wasn't it and having to buy and wait for new seals). I am not a mechanic and don't know all the terms and ins and outs of motorcycles so please bear with me. I'm trying to go from guy who rides motorcycles to a biker like someone said on here before.

If you could please give me advice as into what to check into first and steps to try.

 

your carbs need to be cleaned. sounds as if the enrichment circuit is plugged as well as the pilot circuit and a partial pluging of the main jetcircuit the asperator tubes.

this would explain why you have to start it on starting fluid.

the butter fly do not close completly , it is a function of the carb sync.

replace the boots or clean them and coat them with black rtv

vac tube can hook to any of the nipples it does not matter as long as it is hooked up.

you will need to clean the carbs
you will need to check the valve shims
inspect the rear brake shoes and wheel bearings
front brakes inspect rebuild and check the wheel bearings
ect.............


things to read
http://www.xjbikes.com/forums/threads/read-this-first.110898/

 

Yep, read that - all of it, and click on the links. This will take some time. And know that you WILL need to invest some $$$ to make this 30+ year old bike safe and reliable.
Plan on at least $600. Plan on doing your own work, do not fret that you aren't mechanical.

Ask pointed questions here as you methodically move through refurbishing this beautifully engineered machine back to its original glory. You will be greatly rewarded when you discover the "power band". A lot of smart and eager to help people here.

 

I just took off the two boots and the cracks seem to be only outward cracks no cracks made it to the inside. The gaskets where shot as expected of 34 year old bike. I will be taking your advice of cleaning them and and coating them with the black rtv. For the coating do I coat the inside and the side that attaches to the engine or just the outside.

I will be poking inside the carburetors later tonight and see if I can find any blockages and ordering some new gaskets for the intake boots.

Thank you for the link I will be going over all the information later tonight.

 

just the outside of the boots

 

Okay so far I have cleaned the carburetors ordered a custom made jet kit to balance out the pod filters that were installed. Tomorrow I will probably be either A inspecting the valve clearances or B inspecting the rear brakes and everything I can inspect and lube up while I'm in there.

I've been going over the "information overload hour" ( it should be more like days lol) and I've read up on the brake lines and sadly mine are still the original brake lines. Will the rebuild the previous owner be in vain because of that? He rode it for about 120 miles. Will I need to rebuild them or should I be fine. Also I've been looking at buying some stainless brake lines to replace the stock ones and the cheapest I've found for the kit has been by GALFER for about $120-$105. Is there a cheaper kit or a cheaper kit that you guys now of or could I reuse the same banjo bolts and just buy a long brake line and make my own.

As for my front forks should I rebuild them or just change the oil. The dust seals seem to be in good condition and I don't see any oil on the forks. If i'm going to have to rebuild them what springs and oil should I use. I weigh about 280 pounds will do occasional passenger riding. Also What are your thoughts on gold valve cartridge emulators is it worth the investment. I'm not going to be racing or on the track but I would like to have a comfortable ride with occasionally ridding on the twisty's. Also for the rear shocks can I buy any shock as long as it has the correct length. I'm wanting to put some piggyback shocks (mostly for look) but when I went to proggressive suspensions web site and put my model bike they did't show the piggyback shocks for it.

So far my list for things to do

Final drive oil change
Rebuild or change oil for the front forks
Inspect and replace if needed bearings for the steering, front and rear wheels.
Check valve clearances and swap shims if needed ( is the shim pool still going on)
Change rear brake pads
Change to stainless steel brake lines
Sync and tune Carburetors
Possibly change maxim tank for a 1982 750 seca tank

Things that have been done or in the process of being done
Replace intake manifold gaskets
Coat the intake boots with RTV silicon
Rebuilt Front brake system (- The lines)
Changed the fuse system to a modern one
Rejete carburators for pod filters, cleaned and rebuilt carburetors
New front brake pads
The front end has been swapped out for a midnight maxim one
Front blinkers have been replaced with smaller ones
Oil changed
Small pod filter added to the crankcase breather
Bike has been giving a horrible can spray paint paint job

I'm sorry for asking to many questions and probably seeming like I don't want to do all the hard work. I've been looking around the site and google. I tend to spend a lot of time researching and its a ton of information I find that I tend to get side track a bit by stuff like what is the best gasket material plus I spend a ton of time looking for the best prices and comparing different items and what makes them different and superior to others I literately spent about an hour or two looking up what was the best carb cleaner ( apparently they all suck now since the environmentalist made companies comply with new rules some time in the early to mid 2000s)

Point is Im sorry for asking to many questions I appreciate any and all advice and thanks for the help. I will be uploading pictures of my bike I'm working on tomorrow once I get some better pictures



P.s Here is the person on ebay I bought the jet kit from they do all the calculations for you and send you the kit you need depending on all the mods, elevation etc.. and they have a warranty too (P.s they take offers automatically they accepted my offer of $70 so you might be able to get it cheaper but you only get three tries to make an offer keep that in mind I learned that the hard way when i bought the gaskets and had to pay the buy it now price) I cant post the link (just found out) but they are named Yamaha XJ750 XJ 750 D E J R L 6 Sigma Custom Carburetor Carb Stage 1-3 7 Jet Kit on ebay

 

No apology required for asking questions.
Do not rush through things, taking days to read is ok.
Replace those brake lines, personally I recommend you do that before you ride again. You should not underestimate the importance of stopping.
Valve clearances should be done before any carb tuning.

You cleaned your carbs yourself? Did you get dressed up and go to Church?
http://xjbikes.com/forums/threads/in-the-church-of-clean.14692/
eBay - the E stands for evil, especially when it comes to XJ parts.
Look in the upper right hand corner, click on the XJ4Ever link, buy your parts there, you will smile.

 

Ditch the PODS ... try riding in the rain an engine full of water not cool. Order new brake lines from xj4ever these are the finest lines period.

 

Lol yeah I went to the church of clean. I looked it up the xj4ever catalog. But my handlebars are not stock. I will have to get the top line fitted any idea how to get the new measurement for it. The current one is is bent in a u shape because of the different handle bars.

I can't ditch the pods The bike came with out the stock airbox plus I already invested in the carburetor rejet kit. I believe they sell rain covers for the pods I'll look in to that later but I don't reall plan on ridding in the rain.

I checked the valve clearances the intakes look good all of them are at .005 the .006 wouldn't even go in at all. The exhaust is a different story tho Starting of with the bad one E1 with a 004 E2 with a 006 E3 with 006 going in super easy and a 007 going in with a little bit of force it would catch at first but with a little and I do mean a little bit of force it went in and moved around easily. E4 is the same as E3 But with 5 going in supper easy and 6 with a little bit of force as E3.

I haven't taken the shims out yet as I'm trying to find a source to purchase the shims and don't know if leaving the bike shimles will harm it in anyway while I move the bike around to work on othe parts. (working on a driveway)

 

STOP. Do not pull all the shims out you have to do this one cylinder at a time IE remove shim check number on bottom figure chart for shim you need to replace put in replacement shim . The shim you remove keep because it may be used on another cylinder if it is corret number. So say you have a 280 but need 275 , but another cylinder has 275 but you need a 280 in some cases you swap shims. I needed 3 shims on my bike my local yamaha had a huge bin of shims paid 9.00 $ ea for the shims I needed.

 

1. Get an airbox and go back to stock. The ease of fine tuning your bike will more than make up for the difference of the jets you'll always monkey with and never get happy with

2. If you can see .005 or .006 and say it looks good, you got some seriously good eyes. The rest of us will say that you've got to measure in .mm and doublecheck your math. Your clearance ranges for being in spec are:
Intake: .11-.15mm
Exh: .16-.20mm

 

Awesome good thing I didn't remove the shims lol. I was thinking of possibly swapping out but I might just buy new ones I don't like the idea of checking sizes putting them back in and just to take them back out again.

Hogfiddles What do you mean? I cant find any metric feeler gauges so i went with the inches From the info i found on here It says that in inches it should be between 0.004 - 0.006 for the intake and 0.006 - 0.008 Exhaust.

 

What do I mean?

1. Measure in .mm. Others might be willing to convert from inches to .mm, but I won't. .mm is EASY-- look at the number, read the chart.

2. If you don't measure each of the current clearances, AND pull each of the shims, AND record the numbers, you have NO clue for what shim to replace each out-of-spec-shim with. The FIRST time is the long time. After you do it once (hopefully you keep a record of what you put in) all you have to do is check the clearance then check your records. Remember, it is a REGULAR MAINTENANCE ITEM scheduled at every 5,000 mi.

If you found the inches ranges on here, then you most assuredly would have come across us asking people to re-measure and give us the measurements in .mm.

Make sure you use he correct clearance ranges, too.....there are some incorrect ones printed. I gave them to you above.

If you don't have metric feelers, I highly recommend you get some. You'll use them a lot--you have a Japanese bike.-----

Here is some clarification:

http://xjbikes.com/forums/threads/airhead-valve-adjustment-with-pics.14827/

 

Okay okay I got you now. I swear sometimes I'm slow lol

 

You need to measure with metric feeler (NAPA has them)gauges figure out what you need for clearance then pull the shim there is a number printed on bottom of the shim ...hint reinstall with number facing DOWN figure from the chart in the manual what size you need after you put new in remessure if it is in range your good to go. PS you do not to buy a bunch of shims you would have fortune in shims you might never need or use.

 

ask chacal (len ) at xjforever about the line he can help you out with custom length.
shims ...xj4ever or hogfiddles for the shim pool exchange

xj4ever also sells place holder shims you put in in place of the real shim so you can swap your shims around.

xj 650 bars will work if you want closser to stock

 

okay so I have replaced all the shims that needed to be replaced. I decided since I had the top of to check the timing and I think it's off here are pictures I took. I had my dad hold the bike upright for me and I took the pictures as dead on straight as I could. The Lines at the bottom (don't know the technical name) don't match up it falls in between the T line and a U that's next to T line. Will I need to adjust the timing?

 

This is the beaten beauty I'm working with. Don't know if the miles are correct or not seeing as the miles are exempt on the title and the speedometer is from a midnight maxim. I bought her with a mess of title problems but luckily I was able to contact the person on the title to help me with the mess.

I've got a question that I haven't been able to find probably because it's a no duh question. But I will have to drain the final drive oil if I want to inspect the rear breaks right? I checked the oil and it looked good and the tire seems in good condition. Good threads and not cracked but I still want to make sure the persons who had it before me changed the rear breaks.

 

Picture with the gas tank on and when I brought her home. I might swap out the thank for a seca tank

 

.

 

Read:
http://xjbikes.com/forums/threads/fuel-tank-interchange-information.109290/

A LOT OF OTHER parts are Midnight Maxim parts. Too. Either someone was trying to copy one, or it was one that lost a lot of original parts along the way.

Whatever the case, I'd research to find out if it is indeed one, and then try to restore it to that condition.......

Dave

 

I did, sadly it's not a midnight its a regular 1983 xj750R and thank you for the link

 

Why do you say it's a 750r?

Granted, there's so much wrong with these pictures.... either way you want to go, there's so much wrong stuff. I have lots of parts, I may be interested in swapping wrong parts for right parts ....

I can talk you through a lot of stuff, too

Dave

 

My mistake I get so confused with all the diffrent ways of saying what bike is what i meant R as in the year in the vin its a 750 maxim 22r.

I'm not interested realy interested in doing swaps I'm going to be turning it in to a cafe style bike while going with the theme that its current going for with the midnight look. There's really not a lot of parts im going to be taking off it mostly. A few of the things I will most likely take off it are the battery box and the part that holds the regulator and computer. The rear fender if I can swap for a custom one (don't really want to chop the original one if i can help it)

I'm not really the restoring type more of a custom type. We could work out swaps for parts that I will take off that are in good condition in mine for some that might be damaged say the rear fender for example has broken of near the end and mine is not I'll be willing to swap since im going to be probably cutting of the fender.

Also there's the bike shop near my house that has a bunch of salvaged bikes and I found a Yamaha i think its a seca (it looked sporty). If anyone near the houston/ baytown area in texas wants to check it out (its in a salvage left out in the elements condition) I took the battery strap and the plastic part since mine didn't have it. I was thinking of taking the small oil cooler but I didn't know if I could fit it in my bike. The place is called Land's cycles its a very neat place to check out for projects or parts. I was pleasantly surprised that there was a little gem like that near my house.

 

22r is a model ID code. It designates your bike as a:

1983 XJ750 Maxim USA: 22R

I also still suspect yours IS A Midnight Maxim....

-Black fork lowers gold rims ( that have unfortunately been painted over)

-Black headlight bucket
-gold headlight trim
-black signals
-black rear fender
-black tail light housing
-black Midnight Maxim Cluster
- remains of fairing mount on the forks
-etc......
But the there are other things that are not:

- seat
-bars
-no upper fork covers
-no fancy black w/gold mounts
-etc.....

So, we got the model itself cleared.... why do you say it's not a Midnight Maxim?

Dave F

 

Check your numbers on the head tube, check numbers on your engine...

Read:

 

Okay I'm confused now, no where on my bike or title is there a 33n

I say it's not because the bike didn't have the 33n anywhere

 

Edgar, I'm sending you a private conversation--check your inbox......

Dave

 

Ok, so after seeing the info you sent me, we can finally say for sure tat you bike is NOT a 750 Midnight Maxim. This is a regular 1983 xj750 Maxim. It becomes obvious now that someone in the past had started to either build a 750 Midnight Maxim clone and got stuck when it came to the more rare mounts, or just bought a parts bike (or had picked up a load of parts to just slap on and get a bike sort of together....

Either way, you have a regular '83 750 Maxim with a bunch of midnight parts

Glad to help......feel free to ask questions any time!

Dave F

 

So it's a 1983 Yamaha Twilight Maxim?

 

Are passengers foot rest brackets interchangeable between bikes. Will a 81 750 seca bracket fit on my 83 750 maxim?

 

Not really

 

I never got a response to the timing question I made I posted pictures if y'all could please take a look. The Dots were aligned to the markers on top but the T mark was of by a little bit. Do I need to readjust or is it fine like that? And to readjust is it as simple as moving the the crank to align with the T and then loosening the chain enough to rotate the cam shafts to align with their marks and just tightning everything down again.

Updates

I got the bike running now without starting fluid but she idles extremly high (5K and slowly starts climbing up) . I think it was because I got to excited and put the intake boots back on with out adding rtv to the gaskets and also because I only attended half the church service and didn't completely take the carburetors apart from the rack since I was to scared of messing it up.

I think the problem might be either the gaskets not having the rtv applied to them or the throttle shaft seals (which I'm hopping its not) I will be checking each section individually because I don't want to be having the bike running to long on such a high idle for to long especially with the timing thing that I haven't figured out yet to check where the leak is coming from.

If there are anymore possible causes for such high rpms let me know. I can rule out the intake boots since I've inspected them and they had no crack running into the inside and have coated them in RTV. All the nipples on the boots have their covers on except for number 3 where the vacuum hose is inserted. There are no cracks on the lines. The diaphragms are in good condition with no rips or tears. All the carburetors are getting gas. I had a needle that got bent but I was able to make it straight again (I'm still going to replace it just waiting for the new one to come in the mail).

Things that I'm waiting for in the mail

Engine gasket kit, needle jet, new shifter cover, center stand and hardware, headlight grill, Valve cover bolt seals, New choke lever (mine was broken) Ignition switch cover, passenger foot rest complete assembly minus the hardware.

Things that I'm going to buy later on once I get the whole high rpm fixed.

Stainless steal brake line, Front fork rebuild kit, Fork gaiters, LED headlight kit, New upgrade tapered steering stem bearing, If needed new wheel bearings, Better pod filters than the cheap ones PO put on after market master break cylinder since the stock tilted one does not work with the aftermarket handle bars and If i have money left Progressive 412 series rear shocks and a midnight maxim rear rim ( i decided to go for a twilight maxim lol)

 

likely the timing is off due to timing chain streching. go with it or put in a new chain.
the amount you are off is less than a link

 

Thank you if it's not that bad then ill just go with it

 

If you didn't replace shaft seals.....good bet on air leaks

Did you do a running sync? Didn't see that mentioned

 

I don't have the ability to do a running sync since it's idling to high for me to leave running for to long. I just checked the shaft seals on the side and they all felt and looked to be in good condition. They were soft and when I squished them in my fingers flat they returned to normal. Which leaves me to ask how do I know if they are good or bad lol

 

Have you replaced them?
Does the bike have an uncontrollable high idle?

That's how you know they need to be replaced.

 

Okay just got my new throttle shaft seals and i'm looking at them and they look the same from both sides (to me at least) is there a specific way they are to be installed or do they fit on either side.

 

Orientation does not matter.

 

Just finished going over everything hopefully 3rd time is the charm. I also noticed that one of the carburetors didn't have the diaphragm sitting right could that also have been part of the problem?

I cant wait till I'm done with the carbs so that I can start working on the forks. Hopefully it wont be such a pain in the butt like the carbs.

I will be getting the center stand tomorrow so I will be checking the wheel bearings and the steering stem tomorrow.

 

Carbs will educate you on "all of the little things".
I pulled mine at least 5 times.

 

SOOOOO I put them on and nothing......it's worse than before. before it would idle some where around 1k - 1.5k for a few seconds and then climb to under 4k now it starts at 4k and climbs to 4-5.5k.

applying the choke bring it back down to 4k. the boots have no visible cracks the valve stem seals have been replaced the slides are put on correctly. the carbs have been cleaned. The valve clearances have been set to spec the idle screw is all the way out. is there anything else that can cause a high idle. The ignition wires to cylinder are 1-4, 2-1, 3-3, 4-2.

 

Do your slides pass the 'clunk' test?
With the bike off/ not running. Twist your throttle wide open; let go. Do the butterflies snap shut?

 

using choke and getting a reduced rpm would indicate you are running lean on start up you need to search for vacuum leak.
what kind of air filter? are you still using pods?
could be the gasket under the manafold to carb boots are leaking. or the boots them selves, you can clean them and coat with black rtv.
did you bench sync the carbs? you should only see a little light coming through butterflys when you do.

carbs fully inserted and clamps tight

 

I did replace the throttle shaft seals. They passed the clunk test. Just checked and the butterflies do snap shut.

 

does your throttle cable in the cup and have some slack in it? it may be to tight

 

I'm still using pod filters but the carbs have been rejeted for them.
I used new gaskets for the intake manifold and used a little bit of rtv to seal them and let it set for a day. I also coated the boots with rtv.
bench sync is when you adjust the mixture screws right? If so I did that and have them at 3 turns out from bottom as recomended by my jet kit.
I checked the butterflies and 2-3 had a little bit of light shinning from the bottom and 1-4 had none that i could see.

I will be buying starting fluid and check again for vacuum leaks. I don't see how there could be any ive replaced the gaskets and and seals and made sure the slides were positioned in the right way.

 

bench sync is when you set butterfly s to match each other
you can use wd=40 to check for leaks

http://www.xjbikes.com/forums/threads/how-to-bench-synch-your-carbs.6366/

 

A bench synch adjusts all the throttle plates to be even.

What jet kit did you use and what jets were provided.

Did you remove the air jets from below the diaphragm, and if so were returned to the same holes that they came from?