What's on your bench today?

[Rich2484]

Had a four pot suzuki motorbike engine on the bench today. Can't remember what bike it was off but the exhaust manifolds wouldn't budge so had to cut and remove the studs. Not a job I want to do any time soon.

 

Cleand the starter up aswell as it wasn't working.

 

Mate said he was thinking about giving up on the bike so I might take it on. He got it from a clearence, it was stuck in a hedge at the bottom of the garden.

 

Just need to source a new exhaust or I might make a custom one to fit it. Will try and take camera out tomorrow and get some picks.

[Matthew Arnold]

Matt, to test the breather theory try running it with the cap loose ( on the bench).

 

But my money is on the coil. If you have an inline spark tester such as the Briggs one you can run it and watch the spark. If it grows weak before stopping then it shows that the coil is breaking down. Without that tester, just let it stop and then apply any tester, or even a tiny tach. If the coil is duff there will be no spark, but it may come back as it cools. It will eventually fail completely.

 

Sometimes the coils fail in such a way as they cause the timing to alter, causing misfiring and backfiring too.

 

Tried the breather test and its the coil. We have another older 101 and we ran them both at the same full revs and listened for the different engine notes and smoke colour. There is a good spark on it but not as bright as the older 1. Got a new coil on order ready. It should be here by thursday.

[Johny Walker]

got a km100,sod all compression,every thing init place ,prob is cant check piston wi owt stipping it right down ,unlike an old 2/stroke ,

any ideas ??

[Rich2484]

got a km100,sod all compression,every thing init place ,prob is cant check piston wi owt stipping it right down ,unlike an old 2/stroke ,

any ideas ??

 

sorry I'm lost abit. Km 100 what? Four stroke I take it. If no comp try stuck valve

[Johny Walker]

sorry I'm lost abit. Km 100 what? Four stroke I take it. If no comp try stuck valve

 

km100 engine !!!

all valves working they both move wen the engine is turned ,

[Rich2484]

But are they closing properly, have you checked the clearence on them?

 

Sorry I had a brain freeze moment, was thinking motorbike engines as I was on eBay.

 

Yeah four mix km100 long reach engine. If the valves are losing all the way then it must be piston. Have you had a tester for comp on it?

Edited August 14, 2012 by Rich2484

[Johny Walker]

it can be turned by hand & the vavle move up & down

[spudulike]

it can be turned by hand & the vavle move up & down

 

You need to get the piston at TDC on the compression stroke and check the valve clearances - if someone has done up the rocker nuts, the valves may well be leaking when they should be closed.

 

Take the exhaust off to see if the piston is in good shape or look down the plug hole if you can see the exhaust port from there!

[GardenKit]

got a km100,sod all compression,every thing init place ,prob is cant check piston wi owt stipping it right down ,unlike an old 2/stroke ,

any ideas ??

Compression should be around 90 to 100psi, quite a bit lower than a 2 stroke so it wont seem much in comparison.

 

Its also difficult to judge as the engine has an automatic decompressor to ease starting effort.

 

You CAN do a compression test, but you MUST pull it very fast on the recoil several times to get past the decompressor.

 

The valves need regular adjustment on these engines. They tend to become loose, limiting the amount of time they are open.

 

To adjust, find the little arrow between the flywheel fins and point it to the RH ignition module mounting bolt. Make sure the valves are rocking. If they are overlapping (one open, one closed) rotate another 360 deg until they are rocking (both closed).

 

Adjust to 0.1mm +- .02mm, using a feeler cut down to about 3mm to fit between the side pressings of the rockerarm. Rotate twice and check again.

 

Unfotuneately, as its a 4 stroke engine you cannot check the piston through the exhaust port as the exhaust is passed out throught the valves to the exhaust port.

 

Good luck

[Pat Ferrett]

Gardenkit! any chance you can help out with my question on the previous page ? I recon spuds gone up the pub