Tuned RB250 - 37bhp & 25ft-lbs

Post your Lambretta dyno graphs here! But graphs & spec info only, keep the chat in the 'dyno chat' section ;o)
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drunkmunkey6969
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Tue Dec 18, 2012 11:15 pm

I seem to have a stream of RB engines on the bench at the moment, which is odd after the amount of TS1s i'm used to working on...... This RB was especially interesting for me as not only did i have to tidy up someone elses work first, but i also got asked to work with a 'non-prefered' component list.....and had to work within tight budget constraints. By that i mean it didnt have the crank, rod or packer plate combo that i wanted. Nor did i get chance to implement any crankcase porting on this engine. I also had to live with gearing i didnt like, a bearing set i didnt approve of, and a 35mm TMX where i wanted a 38mm TMX.....but I'm glad of the work, and enjoy the challenge! lol :D

So basically its an RB250 kit, with no welding to kit or casing, no packer plate, and its over-geared. Its using a standard inlet manifold and reeds, Franspeed Race pipe, and a 35mm TMX. Its been ported and dynoed by us to our own spec to give the customer what he wanted......a high power motor - using existing components - within his budget.

I am pleased with the 37bhp and 25ft-lbs considering i had to re-do a cylinder that had been done elsewhere first (arrived with 26bhp - 'tuned'!! :shock: ) and also didnt have the prefered spec i like for these type of motors, but i must say, it now pulls well and has a decent spread for a high power motor, but from a personal/tuners perspective......i wanted it to hold the power for longer at the top end, its just a minor niggle for me, it stays above 35bhp until 8500rpm, but i know it should hold it till 9000rpm when it can 'breath' properly ;) . So when i'm able to make the carb/rod/packer/case porting changes that i wanted to do (customer promises its in the budget end of next season!) it should bump up peak bhp a few points, but more importantly it should hold it longer. Still....good result anyway. :D

Image

As this project gets put to bed (for now) another one starts.......forum member DigDug (John Bond) has asked us to prepare a group 6 scooter for him. He's never raced before, and wants a crack at it next season. So whilst Sean is busy choping and fabbing his frame, forks and bodywork.....im starting on his engine. We'll have a bunch of pics over the coming months, so you can see the scooter develop, and then hopefully John will have a good novice season and get some quality laps under his belt....there may even be a sprint or two, who knows!! :frog: :frog:

We'll keep you all posted. 8-)

Darrell Taylor
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Tue Dec 18, 2012 11:50 pm

good result Dan
what crank stroke/rod was used
was it single or triple port rb ?
feel free to use this link to contact me on facebook and like it(if u like it)
https://www.facebook.com/pages/Taylor-T ... 8819767924

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drunkmunkey6969
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Wed Dec 19, 2012 12:14 am

Darrell Taylor wrote:good result Dan
what crank stroke/rod was used
was it single or triple port rb ?
PM sent.

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GP240
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Wed Dec 19, 2012 12:32 am

Very impressive Dan,

Darrell,
what crank stroke/rod was used
was it single or triple port rb ? :ninja:
Old Lambretta's never die, they get tuned..................

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drunkmunkey6969
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Wed Dec 19, 2012 12:35 am

lol.... :lol: :lol:

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GP240
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Wed Dec 19, 2012 1:01 am

:biggrin:

sorry Dan, couldn't resist haha,

No packer on a 250 the barrel, is the barrel taller or taken up on head gasket.
Old Lambretta's never die, they get tuned..................

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drunkmunkey6969
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Wed Dec 19, 2012 1:09 am

Neither bud, its been a case of re-working other peoples 'ideas'.....id rather not get into it.

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jonny snatchsniffer
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Fri Dec 21, 2012 10:33 am

surely you dont bore into the head and move the squish and combustion chamber a mm or so

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tony
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Sun Mar 24, 2013 12:27 am

That can be done.
Sponsors: Performance Tuning. Ve Uk. Scooter Center Koln. LTH . DRT

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