alpina 350 crank ect to 199

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lms6201
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alpina 350 crank ect to 199

Postby lms6201 » Fri Nov 18, 2011 8:40 pm

have just fitted a 166 crank and top end , the liner needs to be cut down by 3.5mm along with the piston skirt , seems the alpina must have had the cases bored deeper ? i don,t have them for comparison , any advise ,comments ? wondering if i should set the timing to alpina spec , any one here done it before ?



brt650
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Re: alpina 350 crank ect to 199

Postby brt650 » Fri Nov 18, 2011 9:31 pm

Hello,
Sounds like you have a 350 Alpina barrel. Just check the stroke on the crank you have. There are 2 different sizes. 60mm and 64mm. Sounds like you have the 60mm. I have a 64mm crank available, needs a rod kit, if needed. So don't go machining anything just yet.
Or you could get the correct cylinder to suit that crank and engine/bike.
Cheers
brt650



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Re: alpina 350 crank ect to 199

Postby Bully fanatic » Sun Nov 20, 2011 12:21 am

Hello ims6201. It does sound like the 166 is a 64 mm stroke. I was trying to find out what bore and stroke they had on the internet but didn`t have any luck though all I could find was a photo of one. If it is a 64mm stroke the best thing to do would be to have the cases machined th suit the barrel rather than cutting the liner and the piston skirt. That way everything would line up properly. I have used a 206 Pursang conrod in a 199a once and had to space the barrel up by 4mm and the port timing was wrong. It worked alright riding in a section but between sections it took a while to get it to rev high. I think in the history of Bultaco book that a mate has it has the spec`s for the 166 are in there but I can`t get to look at it till Wednesday. As far as the timing goes the later Sherpa`s and Alpina`s used the same timing anyway. The 250`s were 2.6mm BTDC and the 350`s were 2.9 BTDC. At least if it is a 64mm stroke you will have a 349 cc Sherpa though. Good luck. Graham.



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Re: alpina 350 crank ect to 199

Postby brownie » Sun Nov 20, 2011 6:51 am

The specs in the back of the Bultaco Workshop Manual say all Alpina 350's apart from the first 350 M99 (60mm) are all 64mm stroke, all have a 83.2 bore



lms6201
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Re: alpina 350 crank ect to 199

Postby lms6201 » Sun Nov 20, 2011 7:09 am

hi yep 64mm stroke , that was the aim , , i chopped the liner , and piston skirt , deck ht is right but mabey i,ve stuffed up the intake timing



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Re: alpina 350 crank ect to 199

Postby Bully fanatic » Sun Nov 20, 2011 11:21 pm

Hello all. If you have used the Alpina barrel the port timing should be alright, I think. But I`m not a mechanic or anything like it so I have had no technical training but it makes common sense if the barrel and crank are off the same bike then it should be alright as you aren`t moving the piston up or down in the barrel on TDC. Good luck. Graham.



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Re: alpina 350 crank ect to 199

Postby Bully fanatic » Mon Nov 21, 2011 2:21 am

Oh whoops! I was in bed thinking about what I had written in that last post and it clicked. Trimmed the piston skirt on the intake side . Yes that will change the port timing but by how much I`m not sure. You might just have to lean it off a bit . So you might just have to wait and see. Graham. :? :? :?



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Re: alpina 350 crank ect to 199

Postby TriCub » Mon Nov 21, 2011 11:48 pm

How much did you take off the piston skirt. Even 1mm will make a difference. If you fit a read valve to the intake the skirt lenth will not matter.



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Re: alpina 350 crank ect to 199

Postby lms6201 » Tue Nov 22, 2011 6:23 am

same as liner , like i said the alpina cases mut be machined deeper , at a guess same dia as 350 but same depth as 250? , have got it running ok , had a jap ign coil on it , even though it had good spark it wouldn,t fire more than 4 times ,most frustrating, have to get a fr sproket to try a ride , reed valve sounds like a good idea , any body got a spare for sale ? along with a femsa coil , and a fr sproket? 12 th



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Re: alpina 350 crank ect to 199

Postby TriCub » Tue Nov 22, 2011 3:14 pm

I see from your first post 3.5mm . That will change the inlet port timing closer to MX bike which is not to good for trials.
Don't be put of by the Jap coil they are probable more reliable than the Femsa. Make sure that the earth wire from the stator is connected to a clean spot on the frame and change your condenser to one mounted up next to the coil.




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