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steven and daves oppo$ed twin boardtrack racer


sentra

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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!!

allright, seeing as you havent lied to us yet we will get a spare motor, which will net us an extra carb which hopefully will end up so we have a matching pair, and have a fiddell with it.

im trying to figure out what you mean by common head, there is just a big hole, i.e. the barrell

is continuous/pistons go though the plate, and by math we should still have 4.5:1,

(we have to cut up the frame to remove the motor, so probibly wont be changing that for a while, maybe if the motor goes in something else)

lastly re exhausts, i will wait and see what plan copper cock johnny comes up with in that dept, making the exhaust exit smaller than the barrell port will be high on tomorrows agenda

(as it can be done with a hammer)

the motor in the right circumstances starts and idles strongly, it is just slow to build and drop revs.

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the head/spacer should have a squish band in it.

a rough sketch=

img-830095029-0001.jpg?t=1314654947

i say chop the engine out of the frame and whip up another head.

and i noticed the breather on the tank has a twist in it........ is there any chance that fuel could be stuck it the twist? this could restrict the flow. I had a Vespa that wouldnt run after I filled the tank to the top. it turned out that the fuel was blocking the breather. I drilled the breather and it was mint. You could test by getting someone to blow down the breather when the engine is running.

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unsure what breather and what twist youre talking about, but we initially also thought this could be a problem, so i made like uj and i drilled holes in the petrol cap

taking the motor apart at this point isnt really an option i feel as theres still heaps to do yet that could potentially make it run better/good enough/do more burnouts

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dont worry, i just clicked that the twist is just holding the tank to the frame.

have you got a can of ether spray? when the engine is running rough and starting to die, spray ether into the intakes. if the revs pickup, sweet your jetting needs to be richer on the carbs.

what colour is the plugs after it dies? dry, wet, brown, white.

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it currently runs indefinitely/idles, so couldnt tell you without specifically doing a chop, but it builds revs really slowly (and takes ages to come back down also),

we set the points and magneto gap the other night, one of the coils seems to have an issue,

it is making a spark but if we remove that lead it stops, remove the other lead it continues running,

(the compression has to travel up a 5mm diameter tunnell 40mm long untill it reaches the plug, its not ideal but was easy) we were thinking the lethargic-ness may may be related to this, (kind of like timing is super retarderd)

(we need to put a tdc marker on it to see what it is, the timing is unadjustable (apart from via the gap)

on the centrifugal advance, need to check it , might be retarding the timing to regulate itself to lawnmower speed?

the carburettors seem to be both rooted, fuel driping out, eaither both are sunk/jammed what have you,

so we will play with those once spare engine materialises with new extra carb,

will try what you say re eather, also, when leaning the mixture off the idle revs go up unacceptably high but it seems to run better/still rich as shit

also cam ur welcome to use my shit/but it was done on a router/i.e woodworking machine haha

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