took the carbs to church and now I cant get the bike to start

@SQLGuy funny that you just dropped in, I was reading up on your TCI write up!

 

more than replacment caps

 

So I have some high compression test readings and am purchasing a leak down tester to check the seals. I would prefer to not break down the engine, is there a way to safely clean the combustion chamber? I see chemicals for it but do i just spray it into the combustion chamber and try to run the bike? I am having idle issues. Of course this is a moot point if the leak test fails.

 

there is a thread where atf was sucked in through the nipples to clean out the carbon. seafoam has videos of doing the same thing.

using seafoam in fuel tank will also help

 

That is your petcock vacuum line. Cap it when there is no petcock connected to it

 

What chart did you use for you valve clearances?
What were your clearances?
What shim were in it?
What shims are in it now?
What are your current clearances?

 

I have heard of places that do walnut shell blasting through the spark plug hole and/or intake, to clean carbon out of combustion chambers. I've also heard of spraying a small amount of water into a running engine to do this. I haven't tried either and don't know if they're good ideas.

When I did a valve job on the GPz 750 I used to have, I used a soda blaster to remove the carbon. It did a great job. But that was with the head off, of course.

 

Used a chart that I believe you posted in your diy thread,
Exhaust clearances from last summer
.09 .013 0.11 0.11
Intake clearance
0.06 0.14 0.09 0.12

shims exhaust
265. 265. 260. 265.
Intake
270. 265. 280. 275.

I can’t remember from my sheet if the first numbers I wrote down were the original whim numbers or my first estimates, I remember having messed one or two up but my circled numbers were definitely final measurements and shims

and now that I look at it a few of those numbers make no sense as to why I wrote them down... I’m taking the dang thing off tomorrow and remeasuring. Standby for update on the the clearances, pretty confident about the shin numbers though

 

Exhausts are all waay tight, and only 2 intakes are in spec

 

Those were the original clearances and I am remeasuring as I type this. My question is should I measure from sliding it into the side of the lobes or what I can push down into it?

 

Exhaust .16-.20mm
1-2-3-4
.20-.23-.26-(.23/.24)
Intake .11-.15mm
1-2-3-4
.15-.15-(.20/.21)-(.20/.21)

soooo either I was measuring wrong last time or I wasn’t being forceful enough. This time I really forced and slid the gap measurement tool between the shim and lobe. I am going to double check my shims as well since I do not trust my past self anymore. Hopefully this fixes my f****ing idle issue and it was as simple as that!

I also put the carbs back together today after a thorough cleaning using carb cleaner, wires, compressed air, and seafoam. I also replaced the dust covers as well! Going to recheck the fuel levels to be oh so sure they were done right

 

do not force, it is a go/nogo test. if 14 slides in and 15 has to be forced its 14.

 

Well shoot... disregard those numbers then haha

 

Light drag on the feelers is all you want. Now, make sure you’re doing this with the bike overnight-cold. Don’t fire it up first.

 

It is cold and light drag if I couldn’t get it in with a gentle press I didn’t count it, so here are the updated clearances
Exhaust
0.17-0.21-0.22-0.21
Intake
0.11-0.13-0.16-0.16

 

Exhaust 2,3,4 are out of spec too fat
Intake 3, 4 are out of spec too fat

that is uncommon. It makes me wonder a few things:

1. Did someone do a shim swap and do it wrong
2. ARE VALVES HANGING OPEN AND NOT CLOSING ALL THE WAY......do a compression test and find out
3. Did someone swap cams

 

I did do a shin swap last summer! Very possible I messed it up. I did a compression test and they were 165-175psi much too high and makes me think I have too much carbon built up. My family did take it to a mechanic when I was away but I am not sure if they switched the cams, I doubt it.
When I put the correct shims back in and wrap that up I’m going to do a leak down test

 

Performed the leak down test, heard major Air loss from 1&2 via the intake manifolds(25%) 3&4 had hardly any! (So much so I thought something had broken or I wasn’t tdc and double checked 1&2), if I covered them with my hands the noise was more muffled and I could feel pressure, not sure what to do from here and might go take it into a mechanics.

 

somethings not right somewhere

 

Did a leak down test and 1&2 were 25% with air coming out of the intake and hardly any coming out of 3&4. I did it TDC as well. I think I’m going to take it in to a mechanic to check the piston rings and clean the combustion chamber and to double check my work. Valve clearances are in spec as well now.

 

you should take the head off yourself. you might not need a mechanic, if you can find one.
if you do it will save you a bunch of money

 

how can you have so much leakage on 1 2 but still have those compression numbers. even if your gauge is off, their all really close.
me thinks re-tests are in order

 

So retested today, engine cold, carbs off spark plugs out and coils disconnected along with the TCI 1,2&4 around 180, 3 is now at 150. Held the starter button until the reading on the gauge didn’t go any higher

 

Someone correct me if wrong, but I think some engine oil down the plug holes and then compression test will show you if its the rings or valves. If the numbers go up after the oil, its the rings and if not its the valves or valve seats

 

you are correct in that test.
his compression numbers are high

The Information Overload Hour
XJ650 and XJ750 air-cooled engines:
Minimum: 128 psi
Standard: 156 psi
Maximum: 171 psi
Max. variance between lowest and highest: 14 psi

could be carbon build up


but he says he has a leek down issue too.
f) if a cylinder or cylinders have good compression that rapidly "leaks away" (best determined by the use of a Leakdown Tester gauge as listed further below), this points to burned or otherwise problematic valves.

more
2) If one or all of your cylinders are too HIGH in pressure, it means that:

a) you piston domes (tops) and/or the cylinder head combustion chamber have a significant accumulation of carbon upon them, which should be cleaned via some type of chemical treatment or engine dis-assembly and manual removal methods. Note that higher cylinder pressures caused by such build-up may be "masking" or hiding other problems that might cause LOW cylinder pressures, such as worn rings, etc.

b) your engine has been fitted with aftermarket, high-compression pistons, or has had the cylinder head "shaved".

NOTE: high cylinder pressures are NOT a good thing, as they tend to blow out head gaskets and can cause accelerated piston, piston ring, or bearing wear.


You can also test for piston ring and cylinder wall condition by performing a "leak-down" test, which consists of forcing a measured amount of compressed air into a cylinder, and then seeing how long before this air "leaks" out of the combustion chamber and down into the crankcase (past the ring seal):

http://www.dietersmotorsports.com/Compression-leakdowntest.htm


NOTE: be aware that some of the ultra low-priced gauges that are typically advertised on eBay, etc. can be quite un-reliable in their readings, and may regularly indicate a false (low) compression reading.

 

at this point I am going to attempt to remove the head and follow the steps in my Clymer manual to clean and replace what I can. then probably take it into a mechanic who has the right tools to measure and make sure everything is in spec and then put it back together. I have been so confident that this issue wasn't my carbs, I really took those suckers to church and made sure they were bench synched and fuel levels were good! I am hoping this cleaning and replacing of parts will let me get that bike to idle like its new.

Any advice on how to go about this process will be much appreciated. When I do it I will be uploading pics!

 

I’m curious—- are you counting cyl 1 being by your left knee as you sit on the bike: 1 to your left, 4 to your right (which is the correct way)........ or are you Counting cyl 1 by your right knee as you sit on the bike ? Not the correct way)?
Dfox

 

the correct way, as if I was riding the bike left to right

 

NikoRx, before you pull the head (unless you really want to) shine a flashlight into each cylinder and see if there is a large build up of carbon. There are ways to clean the carbon off most of the piston and valves without pulling the head. That is up to you, just trying to save some work.

 

there is definitely some carbon build up in there (especially in 1), I ended up buying the top end gasket and seal kits, figured I might as well check and do some valve lapping to just be sure. I am having some weird stuff that just isn't making any sense to me, high compression test all pretty close to each other and yet 1&2 are leaking air out of the exhaust and intake?

how would you recommend I clean them? the carbs are off since I can't get the bike to idle under 3k, but perhaps I should try this method first and see if it fixes the issue and then break the head if it doesn't

 

Did the oil trick with the compression test, 2,3 and 4 went pretty high up and 1 only went up 5 psi

 

How do I remove this properly?

 

Use a screwdriver and bend the locking tab down out of the way

 

My lovely girlfriend also recommended that haha
Here are the dirty pics I promised

 

i don't see enough carbon on there to raise the compression, doesn't matter now anyhow

 

Agreed, I guess it must be a bad compression tester?

 

What kind/brand

 

Otc 5606

 

While I’m in the head of the engine and cleaning the carbon, I was also going to lap the valves and replace the gaskets and o-rings. I was also thinking of having the pistons measured and rings checked

 

Now you've done it! Gaskets and o rings you have no choice in, as soon as you decided to remove the head this expenditure was sealed. I would also add valve stem seals to this list, and any shims you then need, check the exhaust header gaskets as well.
Just inspect the pistons for scoring, I wouldn't take them off the rods unless you need to. Remove the rings one by one and check the end gap - this is the measure of wear in the rings. If you have someone local by all means measure bore diameter as well.

 

Bought the necessary top end kits from @chacal! Thanks for the advice! The bike only has 5k miles on it so I wasn’t really wanting to remove the pistons. I didn’t see any real scoring but will post some pics.

Learning a lot about the engine in the process, can’t wait to get it cleaned and back together.

Besides adding silicone grease to the o ring components is there anything I add to the gaskets?

 

if your going to lap the valves, for sure put new stem seals in

 

See above...

 

i was trying to reinforce your wisdom, if i offended you in some way please accept my deepest apology buttercup

 

Yep those came with the kit, I will replace them, just got the valves out today

 

Lol, no.

 

Update: lapped the valves and have beautiful rings on the seating surfaces now. removed the valve stem seals and looking into how to properly install the new ones. Any advice would be appreciated, should I buy a special installation tool?

Future plans: cleaning the surfaces of residue gasket, having a bike shop measure bores, piston heads, and ring gaps. then replace gaskets and O-rings. Put it all back together, recheck valve shims and tune/sync the carbs and hit the road!

 

wood dowel rod, square on the end, hole little bigger than valve stem, the rim of the seal should fit the bevel
on the hole

 

quick stupid question. If I had a high compression test and did the oil trick and a couple of them increased even more. that would still indicate an issue with the rings and pistons right? I only see to do that test when you have low readings

 

If you have "high compression" on a 5k engine (is that right it's only done 5k?), and no-ones been in there and skimmed the head, the only cause I can see is you have a duff pressure gauge.
Put it all back together carefully and ride it hard...