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)
User avatar
drunkmunkey6969
Moderator
Posts: 2838
Joined: Sun Jan 04, 2009 1:42 pm
Main scooter: '69 Lambretta GP
Location: North Yorkshire
Contact:

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-)
See our YouTube scooter channel for Tech-help: https://www.youtube.com/c/TheScooterFactory/videos
Darrell Taylor
Dealer
Posts: 752
Joined: Wed Apr 06, 2011 8:43 am
Main scooter: LAMBRETTA
Location: Doncaster
Contact:

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
User avatar
drunkmunkey6969
Moderator
Posts: 2838
Joined: Sun Jan 04, 2009 1:42 pm
Main scooter: '69 Lambretta GP
Location: North Yorkshire
Contact:

Darrell Taylor wrote:good result Dan
what crank stroke/rod was used
was it single or triple port rb ?
PM sent.
See our YouTube scooter channel for Tech-help: https://www.youtube.com/c/TheScooterFactory/videos
User avatar
GP240
registered user
Posts: 149
Joined: Sat Oct 24, 2009 9:38 pm
Location: Manchester
Contact:

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..................
User avatar
drunkmunkey6969
Moderator
Posts: 2838
Joined: Sun Jan 04, 2009 1:42 pm
Main scooter: '69 Lambretta GP
Location: North Yorkshire
Contact:

lol.... :lol: :lol:
See our YouTube scooter channel for Tech-help: https://www.youtube.com/c/TheScooterFactory/videos
User avatar
GP240
registered user
Posts: 149
Joined: Sat Oct 24, 2009 9:38 pm
Location: Manchester
Contact:

: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..................
User avatar
drunkmunkey6969
Moderator
Posts: 2838
Joined: Sun Jan 04, 2009 1:42 pm
Main scooter: '69 Lambretta GP
Location: North Yorkshire
Contact:

Neither bud, its been a case of re-working other peoples 'ideas'.....id rather not get into it.
See our YouTube scooter channel for Tech-help: https://www.youtube.com/c/TheScooterFactory/videos
User avatar
jonny snatchsniffer
registered user
Posts: 277
Joined: Mon Jan 12, 2009 11:53 am
Location: camberley, surrey
Contact:

surely you dont bore into the head and move the squish and combustion chamber a mm or so
User avatar
tony
registered user
Posts: 755
Joined: Wed Jan 07, 2009 1:18 pm
Main scooter: 90ss
Contact:

That can be done.
Sponsors: Performance Tuning. Ve Uk. Scooter Center Koln. LTH . DRT
Post Reply Previous topicNext topic
  • Information
  • Who is online

    Users browsing this forum: No registered users and 1 guest

cron