FZR 400 1WG Cylinder compression value

[Shepsi777]

Hi all,
i was just wondering if anyone would have specific information about the standard compression value for an fzr 400's 1wg 1988 engine cylinders
ive searched a bit & got a value of 135psi however i just want to make sure wether this is right or wrong (cant remember the web page either)
thanks, matt

[taggy]

the 3tj sp is 156psi so i recon anywhere aroung 130ish should be ok. as long as all of your readings are similar you should be ok, if one is significantly lower then you may hav a problem. i think a mate of mine's came out at about 100psi and that ran fine!

[Shepsi777]

thanks for the help, ive got one cylinder at 85 at the minute, gonna check the rest soon, but the way its looking i think ill have to start getting in to valve clearances & such :/

[yamaha_george]

thanks for the help, ive got one cylinder at 85 at the minute, gonna check the rest soon, but the way its looking i think ill have to start getting in to valve clearances & such :/

Hi,
the problem is consistency across the 4 pots. If one is 85 and the rest are higher than 10% more then you have a problem.Even if you had 3 pots at 155 and one at lower than 139 then you still have a problem.
Check you valve clearances and if the bike has stood for a long period the rings in the low reading pot.

With the rings thought to be "stuck" a light machine oil (3 in 1, wd 40 ) into the cylinder will usually free them up, just replace the spark plug in that pot as it will foul with the oil .



Just noticed this is my 5500th post to the Forum

[Shepsi777]

got a value of 85 across all cylinders, piston rings are all worn but surprisingly not blown which is normally what happens to just one, anyway whilst i was there also discovered head gasket is in need of replacement so that is to be done!
checked all the valve clearances and theyre spot on, the heads look to be seated well but whilst ive got the cylinder head off im going to pop the valves out to make sure everything is ok behind them.
rang yamaha technical department too and the standard compression value for the 1wg fzr 400 engine is 135psi.