175cc 'parade racer' tuning advice please

Any advice on tuning a D7 engine for use in a ‘parade racer' would be appreciated. I would like enough umph so as not to look a fool, but nothing exciting. Too old for that!

I appreciate careful assemble would be a start. I have got a D14 barrel which needs a rebore. If it was bored 64mm and the inlet opened out to say 28/30mm but retained the standard porting work?

Any and all advice would be most appreciated.

Hi Arthur not seen you before, lots of help here, try to get to a meeting if you can, and why do you wish to Parade as in "the Parades" we all Parade in a fasion, just some look better than others!!! " Im not going to comment any more on this but may do later.

seriously your questions need to be taken and looked at by a few others.!

Arthur175 wrote:

Any advice on tuning a D7 engine for use in a ‘parade racer' would be appreciated. I would like enough umph so as not to look a fool, but nothing exciting. Too old for that!
Any and all advice would be most appreciated.

When you get answers to this can you please "PM it to me" and also to "Mike Mcdonald" he is the first to mind that desperatly needs it!!

"I just need it to pass to others"""!!!???

Derek

I didn't think I could actually look forward to the weekend anymore that i already was until I read your recent posts

As for weight issues my friend I reckon I could have my son riding pillion and still beat you

cheers, Mike Mc

hi mic i posting from the hotel reception desk only place that has access itally is very behind for access.

anyway your probably right, but i will still look better. i just found out i may well be able to get an earlier flight back so i may ask you to prove that litttle issue is that a bet then i had a bet last year with james cook and won it at the first meeting at mallory, not heared from him since thats the problem with most sotherners thay can give it, but struggle to take it ?

anyway have fun and see you soon

Derek

just one last thing mike we went to the oppera lst night , this guy had huge mouth, and i could not understand a word he said, but it sounded beautiful. "here's the punch line"
kind of reminded me of our chats in the paddock all those years ag,o sounded great but never came to fruition lol

Hi mike just wanted to add to this, I always thought you raced with him as a pilion rider anyway ! LOL

This is a difficult question and probably why nobody has attempted an answer yet.
A great deal depends on how much power you want, how far you are prepared to go with your mods and what parts you are prepared to change.

Your initial suggestion of a larger bore and 28-30mm carb will surely give a performance boost but you may want to do some work on the ports and other things to get a bit more power.

To take advantage of a larger carb. the inlet port would need some opening out and probably making a bit deeper and this is fairly easy to do with a round file or two.

As I'm sure you know, modern 2strokes get most of their power from a resonant expansion chamber - if you don't want to make one perhaps a road going pipe from a more modern bike could be used to good effect.

To make the exhaust system work well the exhaust port would almost certainly need a bit more area which again you could do with hand tools.

I don't know what the D14 port timings are as standard but the transfers look quite a good size.

A relatively easy way to get more power is to raise the compression ratio. A standard head could be modified but a squish band is a big advantage as the ratio rises so you might consider getting a BTW (Brian White) head - details are on this website somewhere.

Have a look at
https://bsabantamracing.editboard.com/t719-amos-todd-186
This was a fast racing bike in 1971 and the mods would be far too much for standard gears, piston and crankshaft so you would need to make your tuning quite mild compared to that but it may give you an idea where to head for more power.

Mick

Hi Mick

Many thanks for your advice. Will have a go at opening the inlet and exhaust a little before trying anything more serious as I would like to use the standard crank, gears etc.

Arthur

Arthur, if you increase the compression ratio look to the fuel you´ll be using. Increasing the CR -- measuring from exhaust port closure to TDC --- will increase power but if you use lower than 100 octane fuel and don´t modify the ignition timing you could have bother. There´s inaudible detonation (pinking you cannot hear) that eats holes in piston crowns as well as causing piston seizures.

You probably know this already. I just need to make off with the wisdom `cos its a long time since I had my leg over...

... a Bantam saddle, I mean!!!

Good luck -- the last parade I was in had me in Norwich hospital and the worst thing was that I was on a borrowed Bantam.

Cheers!

Many thanks John. I assume Avgas (?) would be best with using a fibreglass tank. I doubt the tank has had anything it it for some 10/15 years. Looks perfect inside.

There are plenty of racers with more experience than me regarding fibreglass tanks. They are OK with petrol but I was warned when using Victor Martin Track Fuel (Methanol + Puridin) that SOME fibreglass is prone to swelling and consequently porosity.

No doubt others on here can verify... or kick that one under the table.

Cheers!

Hi John,

Im sure someone will clarify this but people dont use petrol as the ethanol rots the fibreglass tanks, i'm sure there is more than one person on here has had this happen.


Eddie

Thanks Eddie -- I used a fibreglass tank with Icarus-2 Bantam but was only ever using Super (98octane) petrol. There weren´t many fibreglass tanks in my Grasstrack (Whoopee Meth...) days but I remember the pride of one owner -- of such a tank -- turning to dismay, at of all places, Mallory Park. In those days it was a Grass Track and he developed such a leak that he ran out of fuel during a race -- they were very small tanks anyway....

Cheers!

Arthur,
have read your post and answers.
I have built several fast road and a cast iron D14 barreled race engine.
It is possible to have a lot of fun easily.

If you would like to e mail me direct, or I can post here ( as already seen, perhaps a blinkered response !!!) I can share some ideas that may help you have some fun out there on your Bantam.