Hi folks,
i have a little problem while mounting my new 3mboo cylinder ( O-Ring-Conversion) on my DL3 RR.
Did anyone of yours know how tight the original squish (c-head) is? 1,3 mm or 1,5mm or higher.
Problem is......mounting o-ring-barrel with oem yamaha foot gasket 0,55mm, squish is 0,8mm/0,9mm. The engine sounds not healthy, you can hear loud knockings at the top of the engine.
Then i have installed a 0,9mm foot-gasket, squish now is 1,2 - 1,3mm but the engine sounds better but i hear engine-knocking at reving too.
The o-ring barrel no need a head gasket ( -0,25mm ), that means for me, i have to add these lost 0,25mm to the cylinder-foot-gasket....
I have done it with a 0,90mm foot-gasket but engine sounds strange at idling.....
I dont know where the failure is ! Piston is a new meteor one and fits, crankshaft is tested and ok. Before changing the piston ( no o-ring-conversion) the engine runs well without knockings....
Maybe anyone know the original squish rate or have any ideas why the engine sounds bad ?
Cheers
Sorry for my bad english tongue
Have you checked the head and piston top for damage? Also the small end bearings? Spark plug to piston clearance?
Can you please tell me if the 4DL (gold) fork top tubes are aluminium, or just galvanised steel?...
Cheers bud!...
Does a magnet stick to them? Yes = steel aluminium = no
41mm Paoilis, no? Hard anodized aluminum top tubes.
I bought some from a SZR which I had to have reanodized.
I have a 4hw with steel tubes USD's
I was wondering about the gold coloured tubes on the belgarda? 39mm I think, not the gas adjustable SP ones...
Hi folks,
thank you for your replies and sorry for late response.
@Spookdog... yes i have checked the parts again. No damages or contact-signs located at piston, cylinder, crank or conrod.
Forks: The 4HW (4FL) version have a different fork with 39 diameter, at the Belgarda DL there are mounted the golden Paoli ones with 41mm.
@SeaR1ck ...I´ve never tested it with a magnet but it looks like that my golden RR-forks was made from aluminium. I will check it out in near future.
Back to my engine problem:
I have talked to a good old yamaha 2 stroke mechanic and he told me that a squish from 1,2 to 1,3mm is nearly original. At the english DT-Forum i have found a guy who has made the o-ring-conversion too and he wrote that the original yamaha 3mboo squish is about 1,35 +-mm. That´s it !
The 2 stroke mechanic advice me to fuel in high octane petrol (Aral Ultimate 102 Octan) but i makes no differences. Engine sounds bad again, no wonder, the engine is not compacted now with the 0,8-0,9mm base-gasket. The higher octane-fuel should be used for high compressed engines....
I think the lower conrod bearing makes some noises. That means...i will repair the whole engine through the winter period.
Yesterday i have startet the engine again. Big white clouds coming out of the exhaust.... the o-ring at the top head is leaky >:(.
For this year i am fed up with the 125cc TZR. Now i will repair my Yamaha TDR 250. After engine rebuild for 1,5 years an oil hose was buckled and i have dont seen it. After 250 km riding the right piston has blocked. Now the faulty cylinder was checked and honed and a new Mitaka piston is waiting for mounting.
Cheers
Chris
If I was you, I'd put 2 standard base gaskets on and replace the o-ring...
If it's making any top end noises after that I'd try uploading a short Utube clip so people can hear exactly what it sounds like...
It's not a huge job, and I can't imagine the big end bearings letting go before the small end does...