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Post by jeppegh on Dec 8, 2013 20:15:02 GMT 1
Hello, first of all, I try as hard as I can, my Engilsh is not that good. I'am from Denmark.
I have an Autisa big bore kit, I need a piston, do I have to buy one from a Dt175 or a It175? - Is it necessary to do something with the top end? And my last questions what squish is best?
If you Guys have something i could know, or anything to add, it would be very nice!! Thank you.
Best Regards Jeppe Hansen - Denmark |
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Post by cinder on Dec 13, 2013 10:19:46 GMT 1
yes the dt/it pistons are what you need because the ring pegs are at the rear,you will need to machine the base of the cylinder as there is a diffrence in height from the gudgeon pin to piston crown.and also its ideal if you recut the cylinder head to 28 degrees to stop detonation,also tzr radiator is slightly bigger
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Post by jeppegh on Dec 15, 2013 11:01:03 GMT 1
Thank you! Machine the base of the cylinder? Can you explain? I have orded a now Autisa piston, because I didn't know about the It/Dt pistons. Do I still have to carry out modifications to the head?
Thank you very mutch!
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Post by cinder on Dec 15, 2013 12:18:13 GMT 1
The autisa pistons tend to be poor quality,hence people using it 175 pistons or blaster pistons.if I remember correctly the DT pistons have their piston ring alignment pegs in the wrong place and could catch the ports.the need to skim the bottom of the cylinder gasket face is because the Yamaha pistons are lower in height from the gudgeon pin to the piston crown than the autisa pistons(its not a big job on a lathe).
The head could need machining as the ones I've seen use a standard 125lc head which needs opening out to 66mm,also they tend to run hot hence the recut to 28 degrees to help the fuel burn better
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Post by rob99 on Jan 11, 2014 9:18:54 GMT 1
I had trouble with mine it kept nipping up no matter how rich i ran it or how easy i took it, the tight tolerences cannot be good when metal starts getting hot snd expanding
Good luck in getting it running
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Post by tsa on Jan 11, 2014 10:29:42 GMT 1
I fitted a Mito Rad to mine and a DT125R complete clutch to stop that bugger getting hot and the dreaded clutch slip. My std clutch would eat a clutch in a month easy. It would be ok below 5000rpm but slip straight away after that.
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Post by rob99 on Jan 11, 2014 21:40:09 GMT 1
When I had mine I wasn't aware of the other mods like using DT piston etc or I might if persisted with it a bit more
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Post by biffabacon67 on Jan 16, 2014 18:47:37 GMT 1
I had one, back in the day. As above, it always ran hot and kept nipping up. But, when it went, it flew!!! Fab bit of kit.
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Post by jeppegh on Jan 19, 2014 19:17:26 GMT 1
Sorry, i an from Denmark. When you guys says it ran hot, and you tryed nipping up, what does you actually mean? Thanks!
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Post by Roofmonster on Jan 19, 2014 22:34:18 GMT 1
Sorry, i an from Denmark. When you guys says it ran hot, and you tryed nipping up, what does you actually mean? Thanks! Nipping up means the piston started to get very tight in the cylinder and the engine started to seize - "Nipping up" betyder stemplet begyndte at få meget stram i cylinderen og motoren begyndte at gribe |
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Post by simon998 on Oct 5, 2020 18:22:31 GMT 1
I fitted a Mito Rad to mine and a DT125R complete clutch to stop that bugger getting hot and the dreaded clutch slip. My std clutch would eat a clutch in a month easy. It would be ok below 5000rpm but slip straight away after that. Old post but do you remember if there was much to fitting the DT125R clutch basket? |
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Post by tsa on Oct 6, 2020 18:41:38 GMT 1
Pretty simple really
I had to use a thinner basket spacer.
grind a little off the basket rivets to clear the gear selector
fit the complete DTR clutch and the balance shaft and crank primary gears
I never did slip again and is still going strong with the new owner.
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Post by simon998 on Oct 7, 2020 18:06:20 GMT 1
Brilliant. Thanks. I assume it's because of the 7 plates instead of the RD's 6? My clutch was slipping on a ported and +2mm os barrel, I've just picked up a Autisa 175cc (+1.50mm) barrel and head so can't see it surviving that at all. Edit: tsa I just realised youre the expansion chamber guru. Reckon there's anything I should do (Extend downpipe, longer/shorter stinger, different can?) to my large can micron when fitting the 175cc? |
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Post by tsa on Oct 12, 2020 16:28:10 GMT 1
Brilliant. Thanks. I assume it's because of the 7 plates instead of the RD's 6? My clutch was slipping on a ported and +2mm os barrel, I've just picked up a Autisa 175cc (+1.50mm) barrel and head so can't see it surviving that at all. Edit: tsa I just realised youre the expansion chamber guru. Reckon there's anything I should do (Extend downpipe, longer/shorter stinger, different can?) to my large can micron when fitting the 175cc? Well to be honest the micron isngt that good a pipe and it will be no good for the 175 thats for sure. If you need to get good drive and power then you will really need a new pipe made for what you need. |
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Post by simon998 on Oct 14, 2020 18:46:25 GMT 1
Ah I know that would be best but getting a pipe fabricated is out of my budget. Also a bit hard to find over here in N.Ireland
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Dave B
Drag-strip hero
Posts: 240 
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Post by Dave B on Oct 17, 2020 9:29:49 GMT 1
In that case you might be lucky in N.I. There used to be a class for 200cc singles over there. A common trick was to use half a TZ 350 to make a single. Somewhere there must be people with pipes from those bikes. I know. I made dozens of sets of cones for them to weld together to fit whatever frame they had.
I also got a visit from two men in dark suits who were interested in why I kept sending parcels of steel tubes to Belfast during the Troubles- but that's another story!
Luckily one of them was a biker, so it was OK.
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