RB250 SCOOTER SHOOTOUT MOTOR

[Darrell Taylor]

Was asked by a few to pop the dyno graph up of the rb250 motor i tuned that james lancaster rode in the over 200cc standard lambretta class at the scooter shootout
a few people test rode it so could comment on its characteristics


below are 3 dyno runs showing power and torque
with different jetting

purple as used on the road 39.99 bhp
blue as used for the 1/8 and 1/4 runs 41.30 bhp
red as used on the 1/2 mile runs 40.52 bhp

[Darrell Taylor]

LTH , LIEDOLSHIEM i think its called
lightest clutch with amazing feel ive tried 51 racing starts with no slip

[sean brady scooters]

yes fantastic results there darrel ,well done

[Stokie]

That has got to be the most optimistic dyno chart ..............

sorry, couldn't resist!

That's must shift like a scalded cat

[Tom Russell]

All I can do is just agree with what everyone else has said previously, this is just a truely amazing result from what (I think) is a road going scooter, that must be able to break the 100mph barrier in the right conditions, and as I read somewhere else, is also quicker in the 1/4 mile than a Yamaha TZR250!! Wow!

[drunkmunkey6969]

That has got to be the most optimistic dyno chart ..............

sorry, couldn't resist!

That's must shift like a scalded cat

Hindsight is a wonderful thing

And it does shift, Darrell offered me a spin on it at Elvington, much to my delight

[Darrell Taylor]

thanks Eden , Sean

All I can do is just agree with what everyone else has said previously, this is just a truely amazing result from what (I think) is a road going scooter, that must be able to break the 100mph barrier in the right conditions, and as I read somewhere else, is also quicker in the 1/4 mile than a Yamaha TZR250!! Wow!

thanks tom its road going,i had to laugh last weeek when the owner rang me to say he popped to tesco for bread and milk with his mrs on the back pulling up a steep hill in 4th without a murmer he called it a grand tourer engine
id like to add both the power and sprint results have been matched even bettered before by a few others like tim,keith and ian to name the ones i know of with motors from chisel and jb so i dont want to imply or people think its too special , although sprint results are only as good as the weather conditions allow on the day and was told by a few regulars that taking into account the headwind it was a very good performer on a full steel heavyweight chassis
the tzr250 was a demo bike at the meeting it did 90 at 15.5 with 6 speed box and good aerodynamics ,not sure if he was trying? , the scoot did 90.5 14.5 that would be fun meeting the tzr on the road at a set of traffic lights

[Darrell Taylor]

Heres an update on the shootout motor,Eric who owns the bike has continued running around on it doing his wed night ride outs as well as a run up to cadwell park but has been a little lost as to why its so tractable and felt more could be had as he reckons a std ts1 is more peaky
so he stripped the motor out and sent me the top end over for a rework whilst he gave it a once over following its torture at elvington doing over 55 runs up the strip
he found the chain stretched and in need of adjustment and thought he would try it with a close ratio box,he found the clutch had started to slip so fitted new plates and heavier springs along with some new gearbox bearings that showed some wear
i set about the barrell based on the high bmep figures ive seen on the 225ts1 at 39bhp it led me to believe that although this 250 was powerful it still wasnt as efficient so had more power potential left in it,making some changes to port durations to help improve blow down and trimmed the piston cut outs to match the cylinder better
the straight line ignition has been swapped for a varitronic and just thrown on to be fine tuned on the dyno to find best results
collected it today and eric took it for a quick spin and reports no loss in tractability but feels a lot quicker so see what the dyno says

i dynoed it on same jetting as a previous dyno run on a middle of the road jet and have yet to fine tune the varitronic timing to find best results which i hope to do tomorrow

so heres the graph before and after ,didnt think id find this much more especially with no major low down losses so still leaves more to try
i need to dial the ignition in then revert back to old ignition to see if this is where part of the improvement has come from

b4 40.64 bhp
after 45.52 bhp

[Stokie]

B'jesus

[corrado]

It looks poor up to 30mph though.