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Messages - sleepy

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1
General Discussion / Re: Casting polyurethane components
« on: October 26, 2021, 10:18:02 AM »
Don't use silicon if it is near petrol. Silicon is the preferred material for methanol fuel but is attacked by petrol.
Not much knowledge in poly but is it possible to add some sort of fibrous reinforcing into to mix to give it more strength.

2
Wanted / Re: 81 maico GS centre stand
« on: October 04, 2021, 11:25:58 AM »
How much different is it to a 79GS stand?

3
Yamaha / Re: DTI GYT internal rotor points gap
« on: September 30, 2021, 06:42:41 PM »
I'd be interested to see the ignition. When I was a teenager I had a DT1 1970 model I think and it came with a GYT kit that the previous owner had purchased for it but not used but only had Head, Barrel, Piston, pipe and carb. There was a different gearbox with some of the early kits but perhaps the local importer only ordered part of the full kit.
I still think you may have a mechanical issue with the points over .008" as electrically it doesn't make any sense. The duel will change with the gap but it would have to be extremely wrong to stop the spark or the rotor phasing could be out but if its all original I'd doubt that was the case. 

4
Yamaha / Re: DTI GYT internal rotor points gap
« on: September 29, 2021, 09:57:26 AM »
My recollection of the DT1 was that the GYT kit used the stock external rotor ignition but the timing was reset to around 2.4mm BTDC compared to the stock 3.2mm. The timing was set by adjusting the point gap as the backing plate doesn't have slotted mounting holes. This means there is no set figure for the gap. If over 8 thou stops the spark there is something wrong possibly with the mechanics of the points, maybe they are staying open or being shorted. 

5
Spaniards (Bultaco, Ossa, Montesa etc) / Re: Montesa Forks
« on: July 17, 2021, 11:14:45 AM »
The trials forks are leading axle and the MX are inline. Just looking at the one I have and they are leading axle by 20mm in front of fork center line and still at the bottom of the fork.

6
Spaniards (Bultaco, Ossa, Montesa etc) / Re: Montesa Forks
« on: July 16, 2021, 03:54:24 PM »
I'll look but I think if there still here they are trials.

7
Spaniards (Bultaco, Ossa, Montesa etc) / Re: Montesa Forks
« on: July 16, 2021, 10:13:50 AM »
From what model are you looking for? Trials, road,MX.

8
Suzuki / Re: RM400T frame crack?
« on: June 25, 2021, 09:35:23 AM »
Powder coat for show, paint for a pro. Get it magnetic particle tested, you can see a crack through non conductive surface finishes (reduced sensitivity with thickness of coating)
Really, Mag particle testing is normally for cracks you can't easily see with the naked eye like a car crank or conrod to avoid a failure but the frame has already failed and if left the crack would soon be all the way through.

9
Suzuki / Re: RM400T frame crack?
« on: June 20, 2021, 04:29:19 PM »
Common place to crack.
Powder coat will need to go around the repair and a gusset may help as the metal fatigue caused the crack so spreading the load will help stop it happening again.
If you don't repair it will crack all the way through and potentially get a bit ugly with the footpeg close by.   

10
Yamaha / Re: TY 250 piston rings
« on: May 15, 2021, 12:00:03 PM »
The Wossner pistons are readily available in Australia from a couple of sources so no need to go to UK.
The last TY barrel that I bored was still stock bore but it was worn so much that it had to go out to 1mm oversize to clean up. Don't be put off by .5mm oversizes as most cylinders are worn to a point that .25mm won't clean up the wear and require going to .5mm anyway. If you pulled the motors apart on a regular basis and checked the wear as per the workshop manual you would have half a chance but a lot of these motors have never been apart since 1974 and been flogged almost to death.
Best thing is to take the barrel to however you trust to bore it and get them to measure or trial bore it before buying a piston that may not fit.   

11
Yamaha / Re: TY 250 piston rings
« on: May 14, 2021, 01:02:40 PM »
There are some differences in ring around that time. Your piston having 7025 could mean it's an aftermarket, have you looked at the underside of the piston for any markings. Wossner and Wiseco do pistons that fit TY ,DT, MX and YZ from 1973 to 1979 but there rings are different to original.

12
General Discussion / Re: Pre 70 Yam alloy forklegs legal?
« on: May 05, 2021, 04:43:11 PM »
Yes. The later DT1's with the round section swingarm came with them as did the RT1's and form memory were available late in 1969.
It would also be a bit pointless forcing the steel lowers to be used when you could simply fit legal Cerianis or Bultaco or CZ forks which are all better than the Yamaha.

13
General Discussion / Re: xr500 re electrical testing specs wanted.
« on: May 05, 2021, 08:58:19 AM »
That can be a problem. The other wires coming out are the Charge coil and the Lamp coil both are listed at 0.2- 1 Ohm. The Charge coil connects to Pink and yellow wires. The Lamp coil is the white/yellow wire and it tests back to ground.
To identify you will need to check between wires and check to ground.
If you PM me an Email address I can send a scan of the wiring diagram with the resistances drawn on.

14
General Discussion / Re: xr500 re electrical testing specs wanted.
« on: May 03, 2021, 04:12:29 PM »
I've got a shop manual here for XL400 - 500R, 1982 is the date on the front cover.
AC generator exciter coil is 50-200 Ohms (Black/red wire to ground)and the Pulse generator is 510-570 Ohms (Blue/yellow and Green/white wires)

15
Tech Talk / Re: Yam DT, RT, MX fork dilemma.
« on: April 30, 2021, 08:56:52 AM »
Hard to believe a 50 year old Yamaha fork would have some wear. Warranty claim!

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