Messages

1

Tech Talk / Re: Are Yam DT1 head bolts/nuts available in alloy?

« on: December 04, 2024, 11:05:58 am »

Be a relatively simple job if you have a lathe or I could work out a price for you if you only want a set.

2

Tech Talk / Re: 79 Suzuki Rm125 crank seal

« on: December 04, 2024, 11:02:52 am »

If my dimensions are correct the ignition side is 25x44x7 and according to CMSL is still available but the gearbox side is 29x47x8 is not available. I've just done a bit of a search at Bikes and Bits importers and they still list the gear side under part number 41.3-29002(Y) as available but the left side is not but a DT125/blaster seal at 25x44x8 is available under part No# 41.2-25331. These are Pro-X numbers. Bikes and bits are wholesale only so you will have trouble unless you have an account. Send me a PM if you want me to help.

3

Tech Talk / Re: Yam DT1 front brake cam improvement?

« on: August 12, 2024, 10:24:34 am »

Have you checked everything else? I have an RT3 that I ride on the road and the front brake is quite good but when I tried to use an after-market cable it was super spongy.

4

Tech Talk / Re: Circlip on countershaft

« on: June 29, 2024, 09:23:29 am »

This is getting a bit old now but I only lust read it. Circlips are use on a few different brands with success and the one that comes to mind are the Narrow case Maico's including the 490's. The biggest problem going with a clip on a motor designed for a nut is keeping the oil in as the nut is generally used to pull up against a sleeve that the seal runs on and without it the oil find a way out but it will negate the need to oil the chain ever again. I did once against my advice machine a circlip groove into a KX250 shaft after the thread had stripped to keep it working and I didn't hear anything bad happened. A better repair would be to weld the shaft end and re-thread it but that is a difficult repair.

5

Tech Talk / Re: NGK B10E & B10ES

« on: April 01, 2024, 11:49:39 am »

Now we need to see the results from testing of the 2 types to see if in fact the "S" type is Super as NGK suggests. I recall years ago in a former life dyno tuning a turbo 750 Yamaha engine in a speedway car and being asked to try different types and brands of sparkplugs only to find the basic old NGK cheapies seemed to work best and the expensive Splitfire made less power despite the owner complaining that there must be something wrong with the dyno because the guy at shop told him they made more power.

6

Tech Talk / Re: NGK B10E & B10ES

« on: March 29, 2024, 06:23:32 pm »

The "S" means 'Copper core centre electrode (Super)' according to an old NGK book I have so the B10E would not have a Copper core and in theory would be an inferior design. Probably wouldn't be able to notice any difference in the way they work.

7

Other Makes (CanAms, Coopers, etc) / Re: Canam 400 piston

« on: February 11, 2024, 04:31:15 pm »

I think I have worked out they have a 36mm compression height but haven't been able to find a skirt length. If you stumble across it an accurate measurement would confirm things for me but thanks for looking. If your shed is anything like mine you will find it when your not looking for it.

8

Other Makes (CanAms, Coopers, etc) / Re: Canam 400 piston

« on: February 08, 2024, 10:26:23 am »

Thanks that will be very helpful. At this point we are going to try an RM465 piston but will need a barrel lift around 6mm but that will depend on finding out what the stock dimension are. The RM piston works out to be 2mm oversize which will make the sleeve pretty thin but the current is a worn 85mm and there is nothing in Rotax pistons that could be used.
An overall skirt length would help as well thanks.

9

Other Makes (CanAms, Coopers, etc) / Canam 400 piston

« on: February 07, 2024, 04:03:17 pm »

Anyone out there got a 400 Canam Rotax piston they could measure for us? Need to know the compression height and also a center to center conrod length would be handy as well. The piston in the one I'm looking at is out of a Polaris ATV and I suspect it isn't correct as it sticks out the top of the barrel by almost 2mm.

10

Suzuki / Re: RL250 forks - are they 35mm or 1.3/8inch ?

« on: January 22, 2024, 05:02:21 pm »

Honing is ok, example is Mower cylinders with Alloy bores. You just have to clean them properly. Boiling soapy water and a scrubbing brush just like cleaning a cylinder after re-boring. Also need a good hone with parallel stones not the crappy spring loaded things. I've done Maico forks PE Suzuki stanchions as they are meant to be 36mm but the Maico is just under and the Suzy was on size.

11

Tech Talk / Re: CR250M inlet port height different, why?

« on: September 13, 2023, 05:29:25 pm »

I go with the piston ring support with piston at the bottom. Question is how much difference would there be if the high cut side was lowered to match the other side. My answer would be SFA as that part of the port is only uncovered by the piston for a very short time and would have zero effect on flow angle or anything like that. The bottom of the transfer port would be in the same category as the piston edge is masking the port for most of it duration. 

12

System problems? / Re: Is security certificate going to be updated?

« on: August 08, 2023, 06:38:57 pm »

The warning isn't coming up anymore. Just did an update of Firefox so maybe that was the problem.

13

Tech Talk / Re: RM125S Piston rings without notch for pin, eh?!

« on: July 16, 2023, 05:06:16 pm »

Not sure I've seen that on RM125S before but it is common on most Ossa's. The ring peg in the piston is flush with the outer diameter of the piston and the ring gap is around 2mm. First time I sore it I was convinced the rings were stuffed with such a big gap but with the new rings in the bore it looked the same so I looked a bit closer.
Just dug out a new RM piston that has been sitting here for many years and yes it has very narrow ring grooves and a pin the comes very close to the top so that's normal as it seems. Not enough room to file the rings to fit over it unless you take the peg down a bit first but all a bit tricky to do. Just run with it as is, it seemed to work back then.

14

Tech Talk / Re: Needle jet still works with a closed throttle !

« on: May 30, 2023, 10:24:23 am »

All good info and it shows getting a good running bike isn't always that simple. I often get scared when I hear of someone say I got a new Mikuni for my restored bike as the original carb was worn out only to find that even with the same Jet spec as factory installed they run like crap and often seize that nice new piston they had fitted. The differences between carb bodies old and new can be quite marked with Air jets fitted or not and different idle passage sizes ect.

15

Tech Talk / Re: Mikuni hex main jet thread !!!

« on: May 25, 2023, 09:46:32 am »

I think the thread is a carry over from Mikuni being licensed copy of Amal. I have a set of #12 UNF 28TPI taps and die and it is very close, the diameter is 5.4mm and 28 TPI works out as .907mm pitch.
Funny a while back there was a Chinese site selling Mikuni jets in what looked to be common sizes but unfortunatley they had a 6mm thread and the jets sizes were mm and not flow rates. Maybe they fitted the Chinese Mikuni or was that Nikuni or whatever knock off they were peddling. I got some and used the #12unf die on them and they screw in ok and the sizes didn't matter for methanol as every time I drill a jet for meth I engrave the MM size on them. Without looking it up what they supplied as a 200 was 2.00mm and probably around a 450 mikuni.