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Author Topic: 1970 HS1  (Read 425 times)

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Offline m in sc

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Re: 1970 HS1
« Reply #15 on: January 02, 2018, 09:37:40 AM »
i didnt get into too much detail really. ;)

i have a set from summit racing with some extra rolls ordered here and there from there as well  they fit on a 1/4" mandrel for a die grinder. if i was going to do transfer work, i have a set of stones and carbide bits on a desoutter pencil air porting tool. ( i used to work for desoutter actually)


speaking of transfers, i didnt modify any port windows, but theres a side duct that feeds off the main tranfer to the 2nd ports over the intake. there as a large step there i blended into the back of the liner that was just awful.  upon sprating up the trandfer duct, you could see after i was done the mixture coming out, swirling around the bore up to the center of the head (used brake cleaner to look at the spray pattern).



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Rock Hill, SC

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Offline yellowandfast

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Re: 1970 HS1
« Reply #16 on: January 02, 2018, 10:15:57 AM »
on rd cylinders i usually finish them with 400 paper by hand then finalise with scotchbrite on the exhaust. im not expecting miracles on this motor, by any means. it does absolutely run better with the porting, no doubts there. the original porting was absolutely dismal. i think the big restriction now is the pipes without reshaping a lot of ports or adding reeds, which im just not going to do on this motor unless i swap cyls. i mean, its a 90 twin.  :laugh:  they have a ridiculously long straight headpipe and not much room for a chamber in the silencer.  im thinking some moped chambers will fix it right up.

Mark,
I've got some dimensions for chambers that will work.splendid on your 90, depending on how ambitious you feel like getting.....
Oil is your friend......

Manitowoc, WI

Offline m in sc

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Re: 1970 HS1
« Reply #17 on: January 02, 2018, 11:11:06 AM »
thanks,

i think i'll just order soem from treatland, change the headpipes and make em fit. for 160 i can get 2 nice pipes for a 50 thats the same stroke/bore so should be pretty decent. like said, no t looking for miracles and i want it reversible too.  i dotn want to invest the time into rolling cones and welding them up from scratch, but it is appreciated
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Offline yellowandfast

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Re: 1970 HS1
« Reply #18 on: January 02, 2018, 04:58:24 PM »
No problem. I've got piles of pipe/porting carb specs from Yamaha.
For what's its worth, we built a set of ta 125 pipes for my father's LS2 100, and it is tons of fun. Revs to the moon and sounds like your going 125mph, and never touch 55, lol.
Oil is your friend......

Manitowoc, WI

Offline m in sc

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Re: 1970 HS1
« Reply #19 on: January 10, 2018, 09:00:47 AM »
got a test ride in last night on the new tires. the porting seems good, broke (barley) 60 mph on it. (book spec was 53 as top, i hit 61) i put the front sprocket up 1 from stock, and the porting definitely made a difference. I just ordered some exhaust flange nuts for it, going to def have to try to make some chambers for this thing. so, i'd be interested in those pipe specs if the offer still stands.  :thumbsup:
  actually got the twisted front fender a lot straighter on the workbench with a small brass hammer, few rags and a round chunk of steel as a buck.
« Last Edit: January 10, 2018, 09:01:29 AM by m in sc »
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Offline yellowandfast

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Re: 1970 HS1
« Reply #20 on: January 10, 2018, 10:01:05 AM »
Absolutely Mark!

I'll dig them up tonight, along with other race specs from back then.
Oil is your friend......

Manitowoc, WI