replaced orings, still no good.

[cruicent]

Hi,
Recently bought a gk76, ran ok the first few days, trouble starting from the offset though. Last week it was really bad, replaced the orings and smaller funny shaped gasket in the carbs. Its still having a bit of trouble starting though, doesnt idle properly (splutters a bit then dies after a while), and I can walk faster than it accelerates.
I was left with the 4mm carb top o rings, didnt know where they went....
The only adjustments I made were to the pilot screws I think? They were 2 and a half turns out, I put them back to that when I reasembled.
This bike was supposed to be my reliable work horse since the cagiva mito enjoyed letting me down so much, looks like im not to great at picking them.
Any ideas?
Thanks, Toby

[GIXXER_PILOT]

pilot screw is set at 1.5 turns out on most of these bikes. Maybe a change of plugs might help to bring it back to life. Id check the old ones for a decent spark before doing anything else.

[cruicent]

Took it apart again, gave it a clean and stuck in the little o rings I missed, and stuck the pilots to 1.75, it doesnt start unless its over 2.
I havent balanced it though so need to stick it into a workshop to do that.
I played about with the big twisty bit underneath in the middle though....then gave it way too many turns and no idea what it was standard
Im not sure which way the fuel hoses go. Theres a slightly shorter one and and longish one, then the thin one that goes on the thinner part of the tap. Which way round do the other two go if your facing the tap?
Just had a thought. Is it a balance between air screw and pilot? so if the pilot screw was originaly set at 2.5 could the air screw have been set to work with that? No idea how it works as you might be able to tell.
Thanks,
Toby

[cruicent]

Took it to the garage today to get balanced.......oh dear.
problems:
3 cr9e plugs, 1 cr8ex plug
air leak on manifolds
compression:
no1: 170
no2: 140
no3: 145
no4: 80.....
blue smoke ie burning oil
fuel tap only working on carbs 1 and 2
no fuel feed to 3 and 4
plug cap thingys are sparking everywhere.

fark sakes.
Plugs can do, spark caps can change, fuel tap/feed easy.
Not so sure about everything else though.
Compression on a 2 stroke can be either new rings needed or possibly piston or rebore or something. Could it be the same for a gsxr?
Still able to tell if its rings by putting a bit of oil down the plug hole and testing compression to see if it picks up to tell if its rings or is there a different way?
How do I fix an air leak on manifolds...in fact what exactly are manifolds!? The bit the carbs attach onto on the engine block? Is it just a case of finding a replacement from somewhere, then replacing them?
How easy of a job do you recon it could be? Garage said it would be 4 or 5 hours labour + parts so unfortunatly can no where near afford that.
Thanks, Toby

[cruicent]

Oh yeah, after the balance it pulls nicely again :) just wont idle and still a bit difficult to start.

[stripes1976]

pm sent

[Hart]

Hi,
Dosen't sound good I'm afraid. The air leak would likely be perished inlet manifold rubbers but the low compression is much more serious. You can test the cylinder by dropping some oil in, if the compression raises then pressure is blowing by the piston. If it dosen't then you are looking at an issue with the head. Either way you are looking at a big job and may be better off just tracking down a good second hand engine.

[cruicent]

Yay! Moving and getting myself a garage, so have a 4 stroke project on the go by the end of the month.
1st- sort out fuel flow/new fuel tap.
2nd-try and find replacements for carb parts
3rd- open up engine and try not to loose or break anything.............

Replacement engine or top ends seem hard to come by, and dont really want to buy an engine off ebay as Ive had so much dodgy crap off there Im better off fixing this one if there is a problem with it. If the cylinders need reboring or something any one know where to send it off to? Never had to do that before.
Thanks

[cruicent]

Any one know what the piston/bore clearance should be? Taken the top end off, barrels look fine, only had a quick look as had to get to work but seem smooth with no scratches.

[stripes1976]

your bores are probably glazed. shiney and smooth isnt the best with a bore finish.
ring gap is more important
check out this and see how you get on