craig10

The one and 2 piece heads have different journal sizes and are not interchangeable but as far as I'm aware any cam will fit in it's own type of head. I've measured them as follows One piece head cam brand new: Journals 29.93 / 19.93 Lobe nearest sprocket 31.95 Lobe furthest from sprocket 31.50 2 piece head cam (used) : Journals 33.96 / 21.96 Lobes (showing slight wear) 31.7 / 31.3 Clearance of journal to bore in 2pc head 0.1mm measured with plastigage, engine was running fine Check out Vincent Crabtree's stuff in pdf format, there's a whole page on cams http://www.google.co....53899372,d.d2k Craig

There's a 1989 RTL parts list here http://honda-trials.com/_sgg/m8_1.htm If you've got the Honda part number, any Honda dealer can get you it if it's still available, normally the price is the same across the dealers for genuine parts. I normally check availability by putting the number into the parts finder on David Silver's website http://www.davidsilv...by-part-number/ Not sure who folks use for aftermarket stuff. Craig

There's a simple fix for supporting the points end of the cam which would get you by for a while, the guy's running it on the road so would last forever on a trialler http://www.thumpertalk.com/topic/724107-honda-single-cam-bearing-solution-why-not/ I did an outrigger bearing on a one piece head a while ago which worked ok but was massive overkill, see here http://www.thumpertalk.com/topic/842366-honda-cam-bearing-conversion/#entry8715919 You might need to register on the Thumpertalk forums to see the pictures I've line bored a head and fitted a needle roller / ball bearing set up on the cam but not had it running as yet, the engine's in my garage waiting to go in. Craig

+1 on that as advised to me by 'Big John'

Probably the nearest to you would be the Stevenson or Dalmellington clubs in Ayrshire http://www.stevenstonmcc.co.uk/Links1.htm or Cumberland County mcc in the North Lakes area around Caldbeck

From this link http://www.jimsandiford.co.uk/hm-montesa-cota-4rt-seattank-unit-1496-p.asp , it says HM MOTO - MONTESA COTA 4RT SEAT/TANK UNIT HOLDS ADDITIONAL 2.5 LITRES OF FUEL AS WELL AS PROVIDING A "LONG RIDE" SEAT FUEL HAS TO BE FILLED INTO ORIGINAL TANK BY REMOVING (QUICK RELEASE) AND POURING DUE TO FUEL PUMP ONLY ABLE TO WORK FROM MAIN TANK

You'd be best working back from your wanted compression ratio with the piston you have before getting a spacer made, otherwise you might be out of pocket for another piston as well. Remember to check your valve to piston clearances using putty or similar when boxing it all up. You can find how to measure the combustion chamber volume, piston pop-up etc here http://www.britbike.com/forums/ubbthreads.php?ubb=showflat&Number=113079&page=2 , go to the 4th post by Dave_NV, then put your figures into this comp ratio calculator http://www.csgnetwork.com/compcalc.html . You can then just add increments to your head gasket dimension in the calculator to get what you will need. Hope that helps Craig

Doesn't that crucify the rest of the entry though, thought that's why they had gone no-stop to ease the sections and get the entries up. As mentioned elsewhere, very hard on Browny but not many tears will be shed by observers who have been subject to JS's antics over the years.

Here John I think, once they're out http://www.perthanddistrictmc.co.uk/results/results.htm

Shirty altering a section, surely not!! Got to be some video footage finding its way onto Youtube, that would clear the air for sure.

Not really familiar with that specific engine Ross but the normal BSA unit single seal is done by taking the clutch off then removing the large alloy plate behind it. That gives you access to the gearbox sprocket, once that's removed you should be able to pry the seal out in situ.

Not really familiar with that specific engine Ross but the normal BSA unit single seal is done by taking the clutch off then removing the large alloy plate behind it. That gives you access to the gearbox sprocket, once that's removed you should be able to pry the seal out in situ.

I don't know these engines, only the tl125 series but if it's points ignition with a battery and not CDI, check with a meter that the points are definitely making and breaking and that you've got voltage at the coil . If you touch the points wire to earth and then break the connection with battery power on the coil you should get a spark at the plug, making sure of course that the plug body is well earthed. That way you should be able to isolate it to the points or coil. Could be that. the isolating washers are incorrectly assembled at the points wire connection.

If you're going to the bother of fitting new stem seals, get genuine Honda ones if they're available. I've found on my Honda single trail bike that the pattern ones give up quite quickly and then you're back to square one.

Very handy, thanks

Various Honda off roader gear ratios here http://vincentcrabtree.co.uk/XR200.aspx

Maybe the gear shafts are on a different pitch on the 200 and 250 engines (unlikely), or the cut of the teeth is different. If the teeth and the shaft pitches are the same then as you say the mesh wouldn't be right due to the pcd. Maybe the 26t gear is just catching the mesh, ie with a lot of backlash?

Maybe 'hondapants' can help you, see this post http://www.trialscen...post__p__200272 Or g4321, see here http://www.trialscentral.com/forums/topic/9305-tlr250-parts-list/page__view__findpost__p__84990

I'm not really familiar with these engines but there are part fiches here for the 1986 TLR200 http://www.xtremeusa.com/fiche_select2.asp?category=Motorcycles&make=Honda&year=1986&fveh=3710 And here for the 1976 TL250 http://www.xtremeusa.com/fiche_select2.asp?category=Motorcycles&make=Honda&year=1976&fveh=3709

Depends how far you're going but fuel range is always going to be a limiting factor, especially now that a lot of the small village stations are gone.

Good lord ..modern living ...how petty and crass can the law get...has nobody any common sense any more? NO!!

This was the jist of the thumpertalk thread, a shimmed bearing in the housing, drturnip's been running it for a year with just minor oil weepage The scrap heads I got were both worn out at the small end, the large end was actually acceptable on them. I've bored the small end to 28mm on the 2pc head I'm working on, it's a bit nerve wracking doing it on the lathe due to the overhang of the tool from the toolpost. I'll get a video up of it soon. Might not be too difficult on the 1pc head if you bore the chain side wall first to take your large support ring. It's an easier job to fit a bearing on the larger journal on a 2pc head as it's 34mm od with 32mm lobes so it can be bushed to 35 to take a bearing, if I remember right the 1pc head cam has a 30mm journal with 32mm lobes so not so easy without making a split bush as you say. Re the lad asking about the cams, the timings are different, not sure how you could tell the difference without putting them in a rig and timing them with a degree wheel. TL cams are like rocking horse doo-doo, I expect a lot of what's being offered are standard CB or XL cams. Some good info on Honda cams here http://vincentcrabtree.co.uk/XR200.aspx

It's a 2-piece head, originally I was going to use normal ball bearings 2 off 61807 47mm od at the cam chain end, but I ballsed it up and had to take it out to 48mm so I'm going to use a needle roller instead, but it needs a bit more work to keep the inner race in position on the camshaft. Doing it all on a lathe so not so easy to get the accuracy. Pete Arnold at PACRE just runs the cam direct in a needle roller at the small end on his race engines, 28od x 22id. The original idea came to me from a guy called Nigel Houlston who turned down the small end of the camshaft and made a hardened 'tyre' to run it in a needle roller of 28mm OD with the 61807 bearings at the cam chain end. I'm probably going to do a 47mm one as well, as originally planned, I bought some 'scrap ' heads off ebay to experiment with. Think it'd be a struggle with a one piece head without welding in an alloy ring to take the bearing at there's not much material thickness at that diameter. I actually did an outrigger bearing set up on a one-piece head which was total overkill. Someone else had done one just fitting a small ball bearing with shim round it behind the advance retard, if you're registered on Thumpertalk, http://www.thumpertalk.com/index , you will be able to see his pictures here http://www.thumpertalk.com/topic/724107-honda-single-cam-bearing-solution-why-not/page__fromsearch__1 Craig

Hi TL rider, If it's a standard TL head with the domed piston on your big bore engine, the CR must be pretty high! The standard TL piston is dished, or at least the one I've got in the garage is. Some interesting info here http://www.kaila.net/tl125/tl125bigbore.html I've actually got an xl125k2 but the engine architecture is basically the same. I've got various projects on the go at the moment using xl185 and ATC185 parts. I've also just line-bored a head to take roller bearings on the camshaft just to see if it was do-able, I'll upload some pics once it's finished and tested. Like you, I'm also in engineering so these things just have to be tried!