Scooterotica

I recently had a mate of mine turn up with his ts1245 for a dyno set up prior to a big ride out,he had already done I.O.W. on it and wanted a health check and a few bits trying out/dyno testing

the scoot was a fully tuned well sorted motor 62 stroke 70.5 bore giving 242cc (he was told it was 71mm 245) fully welded cases and barrell converted to big ears transfers also water cooled head with a fanless readspeed ignition,running a 34 delly, vforce reed, jl fran race

the first test was to get a baseline to see what it had and a fueling curve
31.57 bhp
23.27 torque


the fueling wasnt bad but the owner disliked the throttle response compared to his mikuni 35 so wanted to try it back on to see if i could dial it in as previous dyno sessions had shown it to be 1bhp down on the delly

i spent some time setting it up on the mikuni and found a good set up but it needed a power jet adding as it was leaning out past peak so safe jetting was fitted and a revisit arranged.

a new dyno session was arranged complete with a power jet added to the mikuni and we set about dialling it in and made good progress,a few tweaks to the pipe were then tried and a different silencer tested and the final set up showed a nice improvement along with been much safer out on the road as the power jet richened up the overrev fuelling to 11 afr which was previously too lean over 13
the blips in the graph past peak were from the power jet and dissapeared during thru gear runs
34.55 bhp
24.34 torque

Any pics of said beast ??

Any info on port timings with a 62 stroke crank or has the cylinder length been altered?

The scoot was ran for the remainder of the season and completed many long runs and improved performance was reported,recently stripped down for a winter freshen up for next season for a planned top end rebuild and replate i was then asked if i could look over the engine set up and improve it further without losing any rideability.,this was quite a big ask on what was already a good motor and when you own a dyno and your work is measured before and after theres no room for error.
the motor was dropped off and i suggested we carried out any changes prior to plating and piston so that further changes could be made if the results were not satisfactory the top end was measured up to check for potential improvement and i drafted up a list of areas to be reworked but other areas i couldnt do anything as needed material added ,the head was not the cr that it was supposed to be so a new insert was needed too
work approved i got on with the cylinder and head but was aware this was someone elses work that i was reworking so felt obliged to make it my own as much as possible
i added 2 extra transfer ports
re angled the 2 existing boost ports
primary transfer roof angles,widths and kickers were changed duration changed
secondary transfers were widened roof angles and kickers redirected durations changed
ex port widened and raised
inlet completely reworked
a second head insert was fully welded and a new dome and squish turned up to provide a wider band width / squish clearance and compression ratio

the only thing left of the original design was the big ears that im not too bothered about and exhaust duct to manifold matching that had been done which id like to weld up but that will be done prior to sending for plating

the motor was quickly refitted to the scoot and ridden over for a quick batch of dyno runs,i recommended the power jet be turned up for the ride over and the owner reported an improvment on the road

we stuck it on the dyno and did a batch of runs that were quite pleasing
the big dip past peak gets smaller with every extra dyno run done and is the rich powerjet setting of which will be set up after the motor is rebuilt / replated cylinder etc although on the ride home reported that it cleared by the time he got it into 4th as it had done previously when up to full working temp.next is the planned strip down/rebuild get the welding done in areas i couldnt rework
37.36 bhp
26.91 torque

development graphs one,two and three
be aware ive started the dyno runs at different start rpm ,i normally start runs as a motor comes onto pipe for a franspeed race approx 5200rpm but im often dropping to 3000rpm to please graph critics

37.36bhp 6+ up from 31.57

26.91 torque 3.5+ up from 23.27

pics of the transfers and ports would be nice if you would be so kind

wack 63 wrote:Any info on port timings with a 62 stroke crank or has the cylinder length been altered?

the original specs were not mine and are a tuners livelihood so wouldnt disclose them

my specs are what my customer has paid to have done and are my livelihood so would be wrong on both parts to disclose them

what i will say is theres often too much emphasis put on port durations which are often a lowsy excuse for port area,achieve the areas then you no longer need the duration a good balance of port areas is whats beneficial and placing the ex duration at a timing figure thats within the pipes designed operating range
on a 62 stroke crank the key is to pull down the durations as low as is possible as there over advanced as a result of stroking

TORQUE IS DISPLAYED AS FT LBS

IVE NOTICED IN THE DYNOGRAPH AREA THAT SOME ARE SHOWN IN NM

RICSPEED wrote:pics of the transfers and ports would be nice if you would be so kind

Ill see if i have any ,took some on my phone but dont have download facility ,ill check my camera for any?