HI to you all:

Here is my problem:

I recently built a new motor thinking of a quick and fun bike, but without seeking the last kilometers per hour, say it did not bother me going over 130 K / h.

The components are as follows: JL RH, Malossi 210, 60 mm crank mushroom type (UNDI from SIP), head 11:1 (gravedigger), reeds MRP (mrpracing) + RD 350 (BGM), Keihin PWK 28, RAMAIR, cases matched, piston machined.

18 º BTDC. Exhaust 186 º - Intake 126 º, 1 mm under the cylinder - 0.5 top of the cylinder, 1.2 squish.

In early tests it was determined that a 48 low jet was the most appropriate and standard needle JJH did well in the stand. Once on the road began testing with a 135 high, but never put the engine at top speed.

The engine feels perfect, sweet, until 4000 RPM, where he finds a wall, starts to vibrate and continuous flat until 5500, after which becames a rocket until I dont know how much (more than 120 km / h in third)

Because I did not have any Keihin needles I changed to a Dellorto 30 PHBH from my Polini engine: the problem persisted. We changed the coil, the same thing. We changed the stator: the same. The flywheel: the same. The reeds:the same.

Faced with such amounts of changes without results we proved a Malossi exhaust and the engine improved somewhat, but not much. We changed the atomicer AV 264 to a AV 262 and it is running better but not perfectly. I tried 16-17-18-19-20 degrees and does not clear the problem: at 4000 RPM begins to vibrate and does not react until after 5500 rpm were it starts to run like a plane.

Is it possibly the crank causing the problem,due the primary compresion being too low? Will that crank work with any exhaust or it will need a special one that will help scavenge?

Aremy timings OK?

Thanks to all.

Saludos desde Sevilla

Bearbeitet 2. Februar 201115 Jr. von santacama

I changed the reeds by carbon ones and everything goes perfectly. Thanks anyway