tinde

http://www.trialscentral.com/forums/index....showtopic=21110

In my parts book (tr34 1988): cylinder 260cc= 12.5177 240cc= 12.5173 200cc= 12.5174 125cc= 12.5172

I had same kind of problem with my '08 270. Riding downhill and getting top of some bigger steps caused the bike to run lean and even stalling, like the fuel was running out. First I checked the float height but is was ok. Then after being pretty p****d out with the whole machine I took the carb out (again) and took a proper look at the carb. The Beta Keihin has only one air intake to the float chamber, as the exhaust pipe so close on the other side. The chamber air intake channel in the carb body is very near to the gas surface even when the bike near level, so when going down enough or after bigger steps when the front of the bike goes down again, the gas can begin to flow out through the chamber air intake channel and its hose, by the "siphon" effect (is that the correct word?). And having only one air channel, this causes vacuum to floatchamber and the bike will be running lean. This was also clearly visible, after knowing what to watch, I went to test it and always when the bike began to run lean, there was some fuel flow in the chamber air intake pipe. To solve the problem, I suppose opening the other air intake could help (as it seems that all other bikes with Keihin have both of them in use). I simply fitted longer hose to the air intake and routed it to go loop high enough and down again where it originally goes. "High enough" was about the height of the gas tap. It has been perfect since.

I'm using Castrol MTX.

Not Irjo, must be corrected: Yrj

They do. For example: N7YCC = BP7ES N6YCC = BP8ES http://www.spark-plugs.co.uk/pages/technical/x-ref.htm http://www.spark-plugs.co.uk/pages/technical/ngkjpg.htm I've used NGK bp6es & bp7es on my rev-3's, never had any problems.

I've changed from '05 to '07. Have just done some running in and been only once driving properly (its winter here now). Bike felt very balanced, engine is quicker (I like). Cant say much more with my limited experience so far, but I really liked it and just cant wait the next season...

Ok, so why not try 6es or 7es for this one? I'm sure Lampkins know their stuff but I'm sure so does the factory.

Can't understand why you're using BPR5ES while factory spec is 7? I've used BP7ES and BP6ES and never had any plug failures with my Beta's (since 2002).

Yes, it has.

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Additional base gasket (lifting the cylinder): reducing compression ratio - yes, reducing inlet duration - yes, but increasing exhaust and transfer duration.

TR35 '91 Synt '93 & Super Trial '93 '90 TR's and older had conventional forks. (of course, correct me if I'm wrong)

'91 TR35 had upside-down fork (also '92 & '93 "240 Super Trial"), these models are rare because Zero was launched in 1990.