Heat seizes...

[soosh]

a.j. I had trouble with my old 185 when it was 1st up together with pinking with a 22mm.Timing was ok,everything else was ok as it was tuned by R.S.Tuning,but couldnt stop it.It wouldnt always do it which was so annoying.Anyway,i eventualy stuck on a 30mm dellorto but maybe in your case a 25mm phbl through the airbox may be better.This type of carb you can increase the floatneedle valve and even adjust the float height aswel.Anyway,pinking stopped,all sorted.Now many people use the old carbs but all engines are different.If your using a Mhale piston in your engine,there is nothing wrong with them at all.I use on in my road tuned 200 although it has been reworked and edges all smoothed off but i only run the two top rings,i used an asso in this kit once but it nipped up as it didnt like the clearence i hadbut the Mhale was fine with it and has been for the past 7yrs.Im sure a had 3" plus a hone,that was my clearence.
Hope this helps

[soullad]

a-j bite the bullet and take it to someone who knows what they are doing and it will save you money in the long run and hopefully give you plenty of trouble free scootering miles Scooters should be about fun so put the smile back on your face

[a.j]

Well I think I ended this sorry episode. I could've sworn to God I'd jetted as per GP200, had a look & I had a 112 main jet in the carb (22mm sh dellorto) so I threw in a 120 & it is running fantastically. I held it on a stretch of motorway today for 3 miles at 60-65 & it never made a sound.

Hopefully this will be the end of it. Thanks for all your replies.

[dapper]

And your likely to get piston slap after you clean up the piston too. The problem is the trace of ally left on the cylinder which then, when hot binds on the piston again so causing another nip up.

[a.j]

UPDATE....UPDATE!!!!! :bouncing: :bouncing:
Took the Lammie down to Brighton saturday, covered about 90 miles getting there via the scenic route, she was superb going on the flat, cruising lovely after I upjetted to 120. But it did still start to 'rat-a-tat-tat-rat-a-tat-tat' rapidly when going up hill, noise stopped when I decreased the revs slightly. Then downhill on the A23 it nipped up but gently, I realised it was because she went onto reserve & gave me no warning....grabbed the clutch quickly & let it out again after I slowed right down & she fired up & got me to the shell garage at Pease pottage (I think). I refuelled & she went fine after that. On the way back I returned down the A27 & she fur king flew home.....I'm assuming that due to the hills on the way there & the warning of seizure rattle that I had so many times before I'll need to upjet a couple more sizes yet?

[156 D]

......in my own experiences of single cylinder two strokes or four stroke car engines it is false economy to fit new pistons in an old bore .......it can never be right.....in fact it is always worse because of the re-honing so clearances are on the piston slap side of things....with the single cylinder engine the inconvenience and the price of the actual re-bore of the cylinder is only secondary to the price of the piston and far outweighs any benefits than just fitting a new piston ......for ease of mind and performance always go the barrel & piston option , unless your 'piston broke'

[a.j]

Fitted a 125 main jet 2 weeks ago & it's been brilliant. I even managed to sit at 60 plus for miles & felt confident enough to resist hovering two digits over the clutch lever.