Project Budget Bobber Bikey

Spent most of fri/sat on the carbs cleaning and put in the larger jets #126main + #42P(thanks chacal) carbs were pretty gunky espeicailly the old jets,. Clunk test, painted the hats, bench sync, back on the bike, put on the pods and took off the exhaust from the headers back...

Started up strong played with the idel screw got her idling pretty decent was responding much better to the throttle then b4. but then....started getting some serious back firing and a lil gas out of carb 2 pod filter...which then the reving would take for ever to come down.

Should I just try to play with the mixture screws got them at 2 full and 1 half turns, check my floats levels? what do I need to read/learn up on next?

 

#126 mains and #42 pilots along with drilling out my enrichment jet with a 1/16th drill was the best thing i ever did to my 650j. She screams! I still get about 30 to 34 miles to the gallon, worth it to me for the ease of starting in the morning and the better performance.

 

rdb very nice xj!! and youre a MD'er too. yea starts no problem no with the new jets but still having some issues hopefully ill be seeing ya on the rds by spring(my goal)

pic of the cleaned, clunked, bench sync, painted hats carbs...



pic of the exaust removed, still gonna cut right when it gets to its largest sand, paint, and wrap these


vid of it idleing, starts idles fine, but after a few secs if i rev wont come back down and if i leave the gas on gas will come out the air filter



was set at 2.5 turns now brought it down to 2 these were newly put in when I got the bike and pic taken b4 i ran it wit the half turn in adjustment

 

very nice. im thinking of doing the same thing with the exhaust on my bike.

 

Does the throttle return when not running? Have you oiled the cable? Does the throttle move freely when the cable isn't connected?

 

yes the throttle seems to be moving and returning porperly so after searching and another thread thinking it maybe be shotty thottle seals and/or vaccum leaks.

 

Well ... as a famous rock band sung in a famous song: "It's a long way to the top".

I've experienced the same and it took a while (I've changed the mains and pilots and needles and springs and needle positions about ... well I dismantled the carbs about 20-30 times) to set up the bike correctly. First: I think the #126 is not enough for your bike. Second, the #42 is definitely not enough.

But ... before we're moving forward do you want to put the exhaust back or you will leave the bike as it is? If you're planning to make any modifications with the exhaust there is no need to try to tune the engine right now. Just do the modification and do the tuning afterwards. So, any plans with the exhaust?

 

No I actually cut the exhaust right b4 the "tapered" end so that the whole thing is the same diameter and leaving it short like this.

 

I think it's not a good idea after all, these engines are running much better with some back pressure in the exhaust system but it's your choice.

The first thing to start with is the leaking of the petrol. Do something with that otherwise you won't be able to set the carbs and run the engine. What I do when I'm putting back the carbs: open the petcock for about 10 seconds. Then I'll tap the carbs with a head of a screwdriver. Then turn on the petcock for another 5 seconds. This will help the fuel valve and the float to settle in correctly.

In your case because you're not using the petcock it's likely that the petrol is leaking from the fuel bowl into the engine then into the oil. Which means not good for you. So, try to install a petcock. The fuel valve is not designed to stand that pressure. It will leak.

Another advice is to secure the carbs onto the frame. Otherwise the weight of the carbs will make the inlet rubbers loose and you would have serious air leaks. Something is necessary to support the weight of those carbs.

If your are ready with those, then yous should start to work on the carb setting. As I see from the spark plugs your settings are rubbish. Nr 1 is kind of a proper setting but I think it's on the lean side. But don't go so far, let's start with the idle.

The high idle means too much air. Which is not necessarily coming from a leak. (However the weight of the carbs can make the inlets loose) You installed pod filters which are much more free flowing and you put #42 pilot jets into the carbs. (The original 750 spec in the UK means #43 pilots and #123 mains). My initial guess is that you have to turn out about 4 turns to have the proper mixture.

So, do the following: Turn the pilot screws into closed position. With this your bike won't able to idle maybe it won't start. Which is fine. If she's idling then remove the carbs, clean them again do the bench synching again because something it's horrible wrong with your actual setup.

So, if she's not idling then start to turn out the pilot screw. Do a turn, check how she's running, then turn another turn, check, and so on. As I said I think you should go for about 4-5 turns.

If the pilot size is fine you would be able to foul the plugs and / or you should have a proper idle. If you can foul the plugs (black all over like the nr3 on the picture above) around 2-3 turns it means the pilot is fine. Also, if you foul the plugs then start to close the pilot screw, half turn for example.

Keep in mind your cylinders may require different settings so you have to tune all the carbs individually. So, try and keep us posting!

 

Thanks Zsoltk, looks like you know your mods, fixed float hieghts stopped the leaking, the US 750 was only 120main and 40pilot thats why I went with what I did, thinking your right about going bigger (read below)

Got all excited went lil crazy with rtv sealant cus of being paranoid about a vacuum leak but kept it neat seemed to work. Re-cleaned, new throttle shaft seals, new fuel rail o rings, and re bench sync the carbs over the weekend. Started it up idled well and throttle came right back down when hit, I was all smiles.

Before I started fine syncing and colortuning, wanted to get a my first ride since Ive bought it just out in front the house nothing long,just to see, kinda live on a hill soon as I go up hill it stalls in 1stgear like not enough fuel, no power? Road down the hill ok turn around, then back up had full throttle open in 1st just to keep it alive moving just fast enough to balance. Shut it down back in the garage. Smile off my face lol.

Idles, have throttle response fine when in nuetral, almost feels like not getting enough fuel in gear? Need to re-re-jet? Def wasnt expecting no power...will colortune and fine syncing fix this or is it def something more?

 

You say it sounds like no fuel, could very well be.
After you colortuned did you do some plug chops with a box fan running to see what you're actually getting fuel wise.
This could tell the tale.

 

I got her neckd for the most part waiting on some of my cosmetic parts to come in(peanut tank, solo seat, drag bars) and get my greaser friends over with a welder and carb sticks/vacuum gauges. Should be pretty close by then...

 

quick update on progress

got my tank back wassell/peanut with pingel style petcock, amazed how much flat black shows dirt and spots lol


drag bars with red grips...not feelin the grips now that their on and so bright


all flat black chop the rear frame and fender


rear shot, wish the solo seat had came in

 

ive got to say, this bike is looking really good! keep the pics coming!

 

I bet your not getting enough fuel wit the pods and open exhaust you are flowing alot of air but its turbulent air and that causes less fuel to be drawn into the air stream so you get a lean mix at higher rpm. On mine I have pods and high flow pipes and run 126 mains 43 pilot and have the needle shimmed .050" and that worked decent until I had a thought about the air turbulence and put the stock boots back on with the pods on the end of them to straighten the flow back out and Holy #$%& did it make difference @6000rpm it feels like the fromt end is coming off the ground. Just my 2cents but this might explain why it idles ok but has no power at upper rpms

 

thanks jamesc and south! really starting to like the look of the ole seca and still more moding to come.

As far as lack of high rpms i havent had it out of the garage at all...waiting on my morgan carbtune the girl got me and fix my mixtures...getting good idle now but havent tried riding her. def post how it all goes once i get it closer to dialed in and if i decide to change the exhaust to make dialing in easier. actually almost seems like im gettin too much fuel

 

Here's a quick pic with the solo seat added....going to basically stay like this until I get it running correctly and tagged on the rd so I can drive to the shop for my hard tail and frame painting. Of course Ill put the tail light and headlight back in(man its hard finding the stock 8inch lens).




Here is the bike after syncing with the carbtune pro. It idles good, I have the throttle cable detached so pulled it up with my hand to make sure its snaps all the way close which it does but still revs away...tried pushing on sync screws at the end there too...ordering another set of carbs hopefully off ebay to see how that goes. Can never hurt to have a spare set anyway...

 

hey just so you know...12 gauge shotgun shells will fit like a glove in those exposed cut frame tubes near the rear suspension...would look good on a bobberstyle like yours.

 

hey thanks dw I think I like the sound of that until I can get it hardtailed...give it a try this weekend, didnt get a chance with the shells today but go it on the rd for my first ride ever

quick edit
This thing rips I was going easy on the throttle and it still felt like it wanted to pull up the front end, then my old dry rotted front tire went out...but feels good to know all the months of work are coming around.

 

yessir

 

I would love to do something like that to my xj700. Looks great!

I'll wave you down if I see you riding around Bmore.

Marshall

 

So did you fix your carb problems?

 

mfchap def flag me down not quite on the rd yet still gotta ins and tag,

tore-yea its was one of the springs right on where the throttle cable is. I had it latched too far forward. I moved it back with a screw driver and bam throttle came back down. So I color tuned and up the rd i went til the flat...waiting on my 8"headlight and new front tire now Ive got some more mods to come of course but some plug chops and should be good carb/engine wise for a bit.

 

finally put a couple miles on today!!

rigged up a tailight/tag holder til i ride it down for the hardtailing weekend, kind of ghetto huh?


painted the levers, and forks, finally got a headlight on and a lil skull/hearts/spades bandanna cus i put bandanna on everything



And for the miles up and down the block several times with some drift stops for plug chops then out to the gas station for some fuel...of course my fiancee didnt get any vids when i was getting it
that mud flung off quickly lol

 

nice!

 

Finally got on way with the hard tail! We didnt get all the way done but will prolly finish up this week and I am completely done can just worry about riding then.





that ugly axle plate will most def be reshaped!





This was a quick mock up before we called it a night. Still a good bit to do...
relocate electric, battery box, some gussets, mount fender and seat and of course paint.

 

Got everything all welded up, gussets, seat mounts, fender...still need paint. Snows on the ground now, but sat supposed to be sunny and 60!

quick b4 shot dont think i have one on here






Def taking a lil longer to finish then I thought it would but Im okay with that, its not warm yet anyway. Also bought one of those sealed high performance batteries, man never had it start so quick.

 

Props. Looking good so far.

 

cool!

 

Are you going to cut the arm out?

 

Now that's what I call triangulated !!
That looks really solid.
Keep at it!!

 

Thanks guys. Got paint on friday night and just got back from about a 2 hr cruise.

Plumber..I thought about removing the swing arm and exposing the shaft and doing like a red and black barber pole effect but decided to leave both, still might expose the shaft.

The rear is def solid I didnt want to just go to the shock mount so thats why I went with a axle plate and bottom rails with a few gussets. Im 230lbs and live in the city lots of bad roads til I can get to where the roads are more fun.

FYI you still need to put the shock bolt back in or you will lose gear oil ooops.

Its def a blast to ride!!

I felt like i could cruise at 60-70 on those back roads and barely touch the throttle but when I did it still pulled hard.

 

Havent gotten any pics on here since finishing, but heres 2 with the wifey...shes really wanting one now of course.

Still waiting on my baffles and now a new rear fender because mine flew off on I83. doh! Also cant believe how fast an xj750 is.

 

She looks great - the bike isn't too bad either!

LOL. Seriously, awesome job. Love the bobber, but as pretty as your lady is, you need to find a way to get her on the road with you!

 

the bandanna on the front is a great subtle touch! adds alot of charactor.

btw what brake master cylinder are you running and where did ya get it, also for how much?