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steven and daves oppo$ed twin boardtrack racer


sentra

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i only just realised (thank to snoozins comment) that this is a true horizontally opposed engine ... i have been having a few dreams about this and been getting shit together to make one ... BEATEN :evil: .

i have however found that with the head plate its often overheats very quickly? . Is that whats causing the backfires on the burnout vid?

this is seriously uncanny because ive been reading and getting info from the older guys at work about the ts3 commer motors etc .

freaking sweet bike .. im going make one asap

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who knows, needs carburettors reconditioned properly / balanced / replaced with a single one so it can atleast have a marginally correct tune, ignition setup properly /( or looked at at all, as far as we know the timing may be heaps diffirent on each points/coil/plug assembelly)

doesnt seem to get exceptionally hot judging by? the amount/smell of old grease and oil burning off barrells?, some guy told steven (who couldnt remeber is name?) to put tape on the open airfilter housings to increase air speed and even that in itself made it run 10x better.

we may have another look at it before grinderfest (10th septemeber)

in reality we will just put fuel in it and do burnouts, it does what it needs to do, hard starting

and rough running is part of the parcel

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semi keen to get this thing running semi ok if youre about that fast135

mainly keen for more drunk burnouts though

Keen for drunk burnouts.

yeah, it was me that suggested closing up the airboxes. 2Strokes dont like open carbs, unless they have been tuned for it.

I think you should get two matching carbs. or get another motor and take each carb off the bike and tune it on the test motor.

the next step would be to sort the exhaust. that shit looks cash as fuck, but if you can get the standard zorsts back on to test, i would do that. just like the intake, 2stroke exhaust is a crucial part of it. those long exhausts could just need a bit of back pressure. ie a washer welded on the end.

and how many cc's are in the head when the pistons are at top dead center? what is the cc of the standard motor?

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aha, thanks kindly for your input,

found some specs when i should be working,

3-1/2 H.P.

bore (mm) 60.32500

stoke (mm) 38.1

displacement (cc) 108.99

compression 4.5:1 (!!!)

which i think brings us to a chamber of close enough to 1cc (per motor, or 2cc in total)

it had a flat head, so we didn't bother measuring anything except piston to head @ tdc , timesed it by 2 and set that as our piston to piston clearance at tdc,

as far as carburetors go, do you think it would be easier to change to a single new china carb, or

is it worth mucking around with the naffed ones we have, knowing that is not a strung out race engine.

(there is no chance of getting the factory exhaust back on, it is integral to the fuel tanks)

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Yeah, can you get your hands on another motor?

measure the compression on that one. then measure the compression on the twin.

I think its safe to say you can up the compression a bit.

whats in the common head on the twin? is there some sort of sqwish band in there? if its just a round ring you may have lowered your compression too much.

a single carb could make things easier in some respects. but jetting it from scratch may drive you insane. if i remember right the carbs that you have are slightly different right? try and source two that are identical and keep with the twin carbs.

and the zorst should have an outlet smaller than the exhaust port on the barrel. this will give it a bit of back pressure.

or go the whole hog and setup a couple of expantion chambers!!

Arbeitsweise_Zweitakt.gif

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2stroke expert-i-ness

See my build?

Has a tatty as sticker on it saying ''active 650''

Sound right for a cc rating? seems heaps to me.

Keen for maximum power from it for high speed runs

expansion chambers

porting

high compression

wish i could run small turbo tbh (will just blow by as ive heard)

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