trapezeartist

There was one of those (or something very like it) at the last trial I observed on. I was intrigued, but by the time I had packed up my section and got back to the car park it seemed that the bike had gone home. Despite looking like a Honda 50 engine, it seemed to have enough poke for the modest climbs on my section, and it sounded nice in a 4-strokey sort of way.

Although I've done some pretty awful things to iron liners in the past, using emery cloth, I wouldn't do it to nikasil. And I'm not sure green scotchbrite is much better. There is a white scotchbrite which is described as "non-abrasive" but I think that must mean "less abrasive". I've never used it, but I might be tempted to try it on the marks left from a piston seizure.

Very interesting. Thanks.

I'm not sure what a ball hone is. Is it one of those things that looks like a bottle brush with a little knobble of abrasive on the end of each "bristle"? If so I wouldn't use it on a 2 stroke cylinder as the balls will go into the ports and possibly round off the edges.

TYs seem to be the frames people modify the most. I'm still trying to come to grips with all this. Looking at your photo it looks like you have also cut off the rear frame loop and the bit under the engine. Is that right? I worry a bit about removing the rear loop in case it allows the rear suspension pickups to clap hands a bit. (Any comments, anyone?) What was involved under the engine? New, thicker, bashplate? Any other extra brackets?

Obviously the piston has nipped-up at some time. It's worth cleaning up the scoring on the piston with fine emery and see what it's like then. As for the bore, you can still see the honing marks at the bottom below the ports so I would guess the bore is generally good, especially as you can't detect a ridge above the top ring. I would clean up the bore with a soft, fine abrasive and see how it looks then. Not sure exactly what to use as I've never done it on a nikasil bore.

Probably doing about 15,000 rpm, though we didn't have rev counters in those days. I worked out the mean piston speed once and it was crazy high. Added to tiny narrow bridges in the exhaust port which wore quickly, and that was the reason for the frequent rebores.

It was an Upton Manx (using Komet internals) that came unstitched due to the big-end failure. I did subsequently use both Parilla and TKM. They were all ridiculously fragile motors. Thankfully the world has moved on.

If it's any consolation, when I was karting in about 1980, piston rings lasted 1.5 hours, it needed a rebore and piston at 3 hours and a big-end at 6 hours. There were some alloy-caged big-ends that were only good for 1.5 hours but I didn't know that. You can guess how I found out.

Quote from the Amazon page: "Smallest meter available (19 inches x 1 inches x 59 inches)" That might prove quite tricky to fit on a bike!

Great value and quality (I would imagine). Shame about the colour.

Could it be that the engine appears to idle at 1800 rpm because the engine produces a spark every 360deg even though it only needs one every 720deg? I know old Hondas like my CD200 work that way. Perhaps the modern Honda in a Montesa does too.

And if you have any doubts over the cleanliness of your fuel you should be filtering it as you pour it in the tank.

I hope I didn't come over as grumpy. I wasn't saying that the riders were insincere; just that the multiple thanks sounded insincere. I'm totally happy with the friendliness-factor in trials (and every other sport I've been involved in).

Oh good, a Yank. I can offend you too. Easy target! (There I go. Done it already.) But thanks for all the advice, guys. I'll have to draw a conclusion on the frame breaking issue, and for the moment I'm going to conclude that it probably only affects a few examples. As I'll be buying something several years old, I suspect that if no-one else has managed to break it, I probably won't either. I have to say that having looked around a couple of GGs at a trial earlier in the week, the welding was pretty ugly. By way of contrast the welding (bronze welding probably) on a Whitehawk Yamaha was absolutely beautiful. I just had to stand a gaze on it with awe.

Thanks, All. Broken frames are mentioned again, like in my GasGas thread. However if I bought say an '09 it will be 7 years old. If no-one else has broken it by then, I don't think I'm likely to.

May I offer a slightly different angle on this? As a returner to trials after half-a-lifetime, I am pretty much a newcomer. Until I get a bike of my own I'm attending trials and observing. I offer myself as an observer in order to help, learn, get involved and because I enjoy it. I don't observe in order to be thanked, paid a few quid in petrol money or given a cup of coffee. Last Tuesday I observed on a trial, and a seriously chilly day it was too. On the last lap I would guess about 80% of riders said "Thanks for observing." Exactly those words, every time. When it's repeated over and over it starts to sound insincere, no matter how sincerely it's really meant. I didn't feel any better towards those who said it, or worse towards those who didn't. Perhaps it's just me.

So, plus points for '09, '12 and '13. Marks against for '03 and '09. If it's not too much to ask, what are the reasons for these choices? Thanks.

I did search on "cracked frame" and it makes pretty scary reading, especially the bike with the steering head just about hanging off. But really how common is this? Is it just a few hard used and abused bikes? Or frames welded up by the apprentice? As far as the "Beta or GasGas" question is concerned, having worked with Spanish companies for many years and lived in Spain for a while, I have a natural leaning towards the Gasser. But things like this may tip me the other way. Funny, I've never really thought of "Italian" and "quality" belonging in the same sentence together. (There. The other day I offended the Belgians, and now the Italians! Will I have any friends left?)

If I was in the market for a secondhand Gasgas somewhere between 2003 an 2012, which would be the significant model year changes I should look out for? Times when they actually introduced something new and (hopefully) better, rather than just some new graphics and a bit of bling.

If I was in the market for a secondhand Beta somewhere between 2003 an 2012, which would be the significant model year changes I should look out for? Times when they actually introduced something new and (hopefully) better, rather than just some new graphics and a bit of bling.

You could try this stuff: Demon Tweeks Tyre Softener. The real thing, or snake oil? I've no idea, but the MSA saw fit to ban it from use in control tyre classes.

Oh dear. I should have known I would offend someone. But it's not rare for me to offend someone, so please don't be offended that I have offended you.

Blimey, you learn something new every day. I've never heard of zerk fittings. This must be something new and hi-tech and wonderful! Googled it: just grease nipples. So to all those zerks out there, I'll continue to call them grease nipples. If you're going to clean down a bike with a pressure washer it's pretty inevitable that the blast of water is going to get into the bushes. After all, the swing arm and mono linkage area is just the bit where mud accumulates and is difficult to remove any other way. So the ability for easy, frequent greasing seems like basic engineering and should be designed it. But if it's not, I like breagh's suggestion of using chain lube. After all that's a lubricant designed to find it's way into inaccessible places.

Although a heat pump is a brilliant device in the right application, there are limitations, especially with air-source (reversible aircon). The Coefficient of Performance drops according to the temperature difference between the evaporator and condenser, so the CoP is not that great when outside temperatures are very low. Also the condenser is liable to icing if the outside temperature is below about 8oC, which further reduces CoP either due to the ice itself or a de-icing mode. Ground-source heat pumps are much better, but the installation cost is much higher.