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Triad, if the primary drive crankshaft sprocket has a cush drive, then it is an easy job to change the crankshaft seal, but you need to buy a special puller for the cush drive. These pullers are available from vintage OSSA parts suppliers in the UK and USA. Buy a primary drive cover gasket and crank seal holder gasket while you are at it.

Hello guys, sorry to resurrect an ancient thread... I have an Ossa engine requiring new crank seals as it's drinking gearbox oil. I'm kinda skeptical about doing the job myself as I never worked on such an old bike and I don't have the pullers. Is it hard? What kind of pullers do I need? The engine should be from a late 70s Pioneer, has the coarse teeth levers and runs, so the Motoplat rotor is good and has good compression. I'm in Italy, can't find a shop willing to tackle the job for me.

There always seems to be a focus on fuelling and I recognise there's been some success with playing with it but I don't know what it is particularly but I like the idea of weak spark being a culprit. Especially in this case where the OP has gone to great lengths to prove it (apparently never solving it tho). I fully understand the fuelling has to be right, and 2 strokes are renowned for clogging jets etc so I get where the focus on fuelling is coming from. But the fact gassers are so well known for poor starting even on very new machines would point to something else at least not helping. Went to the Reg Bowker yesterday and watched in awe as the riders jumped on their bikes after refuelling and with just one kick we're off again! Even gassases! No magic dance or superstitious routine. So it is possible to achieve.

Assuming there is not an electrical problem, making the starter jet richer can help. Does it have a Dellorto? If so, they have replaceable starter jets. When I did not want to wait for jets to arrive for my old TXT321, I just enlarged its original #60 starter jet hole from 0.023 inch to 0.028 inch (making it approximately a #70). Much easier to start! Figured I had nothing to lose, as I could just solder up the hole and re-drill to original size if it made things worse. The jet number is the approximate diameter in millimeters, so a #60 would be about 0.60 mm in diameter. When I drill a jet, I obliterate its original markings so the next guy is forced to measure. But I also always supply a full set of note with any bike I sell.

In the 5 years since this post went cold, has there been any development on improving poor starting?

Had my first "cold" ride today. (It's not actually cold, maybe 8°C) but i did get both hands drenched within the first 20 minutes. Anyway, heated grips are absolutely amazing. I went with this kit from splat shop https://www.splatshop.co.uk/heated-grip-kit.html I binned of the resistor and switch for high/off/low And just wired it into my headlight wiiring instead of high beam. So now i just use the pre-existing switch on the handlebar. I rarely ever ride at night so thats no issue, but it's just the swap of 2 spade connectors to return headlight to normal.

https://youtu.be/9TH3osNOdBY?si=QsjThBvRpJ9lP

Ok another trial last weekend which was harder. I was pretty switched on for some of the first lap. Then got progressively worse. Think I'll try the kit but need to get past Christmas and cash flow issues. I could just take money from family account but I expect the wife to keep to a budget for play money account so I probably should. . .

Thanks. Yes, I saw the spaltshop review but was just treating it with healthy skepticism given they're flogging them so it's good to hear your take. I think I've come to the conclusion the tyre might be good but possibly too new to the market (6 months ish?) to have any long-term feedback. I think we'll quite possibly give it a try in the new year

had one when they first came out, slightly harder side wall than an x-light (I've split 2 of those so wont buy again), plenty of grip, and no downsides for me, I ride on rocks/streams, and lots of mud and very pleased with it. look up splat shop in the uk for a review.

32x spokes wheels save 1.450kg !

Gotgas, I would try the Kenda IBEX trials specific tires in a heartbeat. I’ve read several reviews stating people love the tires. Kenda also has an exceptional reputation in the tire industry. The only problem I have with them is they aren’t available locally for me. Go for it and don’t worry about it.

Evening mate. No didn't get any reply so stuck with the standard plug but will try a 4 soon

32 spokes rear wheel, 750grs less than 36 spokes wheel. Dry weight : 71.5kg (- 6kg)

It's a radial rear and it's stamped for 'trials competition use only' right on the sidewall, I'm guessing it's a trials tire worth a try. It's not like a rear tire lasts any longer than one season anyway. + If they are any good you can bet the price will increase.

Yes faussy I agree .He could also try the MITAS PRO and the PIRELLI MT43 , I have not tried them but they look like Trials tyres. At club level I do not think tyres make much difference. That is also true of the bikes that people use , regular competitors know that a old Fantic 125 twinshock will beat a 300 Vertigo with the right rider on board. It makes one wonder why people bother at club level with all the expense. There is a review on instagram by an competent Australian rider and the Kenda IBEX gets a good review all round , the only exception being that the tyre folds when pushed hard.

I did not know anything about the Ibex, but it's a great name for an off-road tire. A quick search revealed the Ibex endurocross tire. I would not ride that in a trial! How could faussy be so wrong? Turns out, there is a trials-specific Ibex, the K7104F and K7105. https://powersports.kendatire.com/en-eu/find-a-tire/motorcyclescooter/mxoff-road/ibex-trials/ Yup, that looks like a trials tire. But the durometer of the rubber would still be a big consideration for me. See: https://www.electricmotiontech.com/home/trials-tires

Disagree. Not everyone is wanting to go win their local trial, and I guarantee if I put the Kenda on I would still beat 90% of the riders using michelins. FYI, I haven't even tried one yet, but I know just by looking at it, its a decent tire

Michelin , Dunlop D803 GP , IRC Rear . Anything else is not a serious tire/tyre for the sport at this present time

Restoration of a pair of original 4RT 32-spoke wheels. Sandblasting, painting, and polishing of the hubs, SKF bearings. Cleaning and treatment of the spokes. Deglazing of the discs. The weight saving on the front wheel is 700 grams less than 315R wheel! Spokes nipples are aluminum, brake disc, different hub, and four fewer spokes... a significant weight reduction.

Welcome! That’s great to hear about your sons. Would love to see some photos of them doing their thing. I can’t get my son interested. How’d you do it?

We were on the right track. Took the bike to my local dealer, got instant service. Traced the issue to a lack of fuel pump pressure. The control relay was somewhat corroded. Replace it, fuel pressure back to normal, problem solved. Happy days.

Time for a new rear tyre. I got to see side by side the Michelin X11, IRC, and kenda Ibex and the ibex was definitely a nice gummy compound, softer than the other two. I assumed the downside of them must be the wear rate but talking with the vendor and googling it doesn't appear to be the case (weirdly the opposite in fact). There is a suggestion the ibex side wall may be slightly stiffer than a x-light but that's all. I can't really seem to find a negative thing about them. So why would I buy a £140 tyre when an ibex is half that? Looking for input from anyone with firsthand experience with them...

Hi, new to the group. I have joined as this looks like the place for everything trials related! I used to trial myself around the mid-90s as a young teenager. Now my sons have shown an interest so I have supported them into trials. They've been on Osets the past year as an introduction to the sport and my oldest (13) just upgraded to a Gasgas 125.

Non-powerjet. If you want an OKO, the model is K-100 and people usually run a 26mm or 28mm