Another camchain question !

[tomo]

It looks like I`m going to have to whip off the cylinder head of my GS750 (re: previous thread regarding starting problems) and check out the valve seating etc. Think the camchain is ovrdue for replacement too, but don`t really want to take the engine out and split the cases, so was thinking about a split link chain. Trouble is I have mixed feelings about using one. I guess so long as its done carefully it should be ok, but I`d appreciate any views or advice about this. Thanks.

[madjack57754]

The cam chains are of a endless design, I've split the chain using a Suzuki tool just for this job, and used the old chain to pull the new one through the lower guide box. Then the tool is used to reset the pins in the link to make the chain whole again. Very slick and you don't have to split the cases

[tkent02]

I looked at your previous post....

your compression numbers were 55,55,65 & 75psi... fairly close together but all low. A lot of variables go into compression numbers, cranking speed, throttle position, altitude, air temperature, engine temperature, cam overlap, etc, etc. Even different meters will read a lot different on the same engine. If it isn't smoking or using oil, and especially if it was running fine before your starting problem began, it does not seem likely that low compression is the reason it won't start. I would try a different compression tester, when the engine is hot, cranking fast, throttle open, do it all again. Make sure the ignition is working correctly, check the valve clearances, make sure there is fuel in the carbs, and it is getting into the cylinders, check everything. In short, just make real sure the problem is internal before you pull your head off. No point opening a bag of worms if you don't need to. If the compression was bad it would have been running poorly, especially a rough idle for a long time.

[DimitriT]

Just to add to the previous message..

also check your valve shims for proper clearance
and redo the compression check with some oil added to the cylinder
compare the dry number to the oiled number to see if the compression problem
is due to rings or valves.

[tomo]

Thanks for the advice guys. I did try the test without oil first and then with oil in each pot, but only got a few psi improvement. Unfortunately can`t re-test with engine hot as the old girl won`t fire up at all. Fuel is getting through, ignition timing fine and good spark at plugs. Have`nt checked valve clearences yet though.

[sissonk]

Not sure if this is of help or not but on my GS 850 if the vac line to the petcock if leaking or broken off it is impossible to start. don't know if the 750 uses the same system or not
Good luck

[Dave8338]

Just to add to the previous message..

also check your valve shims for proper clearance
and redo the compression check with some oil added to the cylinder
compare the dry number to the oiled number to see if the compression problem
is due to rings or valves.

A side note to DimitriT's oil to the cylinder trick, make sure that you use a known amount, ie. one cap full per cylinder (whatever you use to measure). I use an old syringe I got from the vet. Measure your amounts exactly for each cylinder or your numbers won't be accurate. 1/2 ounce works well.

[tfb]

What makes you think your camchain is up for replacement?

[49er]

Tomo
Do your top end strip down before you order any parts. If you find excessive piston and bore wear, you will need to check out the bottom end as well. At 90,000 miles you may need more than a top end refresh. I stripped my 850 and found the chain in reasonable condition after 78,000kms. The chain guide next to the exhaust was okay, but the tensioner guide had deep grooves in it and the rubber/plastic was breaking up. I fitted a light weight and slightly longer Tsubaki EK cam chain with a joiner link as discribed in a previous post. Also renewed both guides and the idler. I could have re-ringed and honed the bore, but decided to increase the capacity and CR.
Good luck

[headsbikesmopars]

Be sure to OPEN the throttle when checking compression. Be surprised how often this is overlooked. This will give very low numbers. Good luck, Terry.

[tomo]

Thanks again for the advice. I don`t know for sure that the chain needs replacing, but it is getting rattly and the engine has a lot of miles on it. Thought while I am stripping the head, might just be prudent to do replace the chain while the bike is off the road.