jrsunt

A 125 would work well, they have enough bottom end to pull away without having to use the clutch excessively and as she progresses the 125 is more than capable when you start exploiting the power at the top of the RPM. 125’s enjoy been ridden hard, if she’s confident with throttle, clutch and brake timings a 125 is a lot of fun. I enjoy riding my lads Gas Gas 125, it’s highly manoeuvrable and a lot lighter than the Mont. It only lacks power on the really big stuff. The 200cc bikes do tend to ride more like a 250 than a 125, a little more flywheel and inertia keeps everything moving forward a little easier.

I’d be checking the internal diameter of the con rod small end. Even with the slightest play it will give a knocking noise. The piston doesn’t do much other than support the rings, which do all the hard work and wear considerably. If the con rod is slightly out of specification everything will wear as it won’t be runnng true and it will do the same again

Take it all off, it’s just stuff for homologation purposes. All the vapours and fluids end back in the air box, not what a competition engine needs. (The bike will empty the contents of the crankcase back into the air box when upside down) Remove at the air box and bung the hole. Firstly start with the petrol cap breather, cut it to about 6” and tuck it into where the throttle cable goes. The cylinder head breather can be shortened and tucked in down the left side of the radiator/frame legs as can the ht coil wiring. (Loosening the bolts and front engine mount helps get them in) The fuel pump breather down the right side of the radiator. The crankcase breather runs on to the sump guard at the rear. The electrics on top of the crank cases can be made much neater, do away with the bank angle sensor nearest the shock. Unplug it from the rubber boot and put a link wire connecting the outside terminals together ( i think there’s a yellow, white and green in there). The relay wiring comes down from under the headstock and sits under the exhaust. Now that you’ve got room under the tank from removing the junk, the relay wire can be shortened and attached under the headstock using the fluid catch can bracket. I have the Mitani condenser, it’s very small which allows it to go into the rubber boot. I’ve removed the bank angle sensor connector which makes more space in there. The only thing I have left is the rectifier and rear brake reservoir so I made my own carbon fibre bracket to hold them rather than the hefty steel one. Hope this helps

I also think it would slip when removing springs. The 4rt clutch is quite grabby compared to other models, Elf and light gear oils emphasise the issue more so. The early ones with the small master cylinder were particularly bad. Setting the lever up correctly is quite important and the dimpled plates really do help, much more progressive and will not slip, ever. The Mitani clutch pack is awesome, starts in 1st gear and is quite a bit lighter…. expensive too, but a good investment. I believe there are titanium springs for these, not sure if they give a different feel or are just purely for weight saving

They give a little more leverage for the shock, it’s hard to explain how it feels, but the shock feels a lot more responsive to rider input. There isn’t much difference when you line them up side by side but it does feel better to ride with. I prefer the feel of the Showa shock compared to the RCV thingy and run with about 7 threads showing below the lock ring. Be careful though as it can be a little more prone to throwing you over the bars until you are used to it. Make sure your bearings and bushes are good. 1mm of play in the linkage turns in to a lot at the rear wheel. Don’t skrimp and buy the all balls kit, Always get the genuine Honda bushes and most importantly the spherical bearing, it’s a world apart from all balls quality

I used a bum bag for a couple of years but found they wriggle around too much. Last year I used a fender bag and it was nice to have the bike carry tools instead of me. They are a bit limited for room so you’ve got to be ruthless with what you put in them I don’t carry a drink for me but 250ml for the bike instead. The rucksack allows plenty of room for everything you need but it’s easy to go overboard and end up carrying too much weight, Make sure tools are wrapped in a cloth or something and don’t move, otherwise they’ll rub a hole in your back

The 10w40 should be more than up to the job unless it’s very poor quality. These things will happily change up and down without the clutch just by matching the revs. My gearbox is 20 years old and never been touched!! I have always found 10w40 to stand up better to heat and more abuse than Elf and light gear oils. The lights ALWAYS give a better clutch when cold but they get very grabby and snatchy when working hard. I run Motul 300v factory line for both engine and gear box. **** when cold, but isn’t affected by heat and hard riding. Another thing with the Mont clutch is that you generally need full pull of the lever to find neutral. Any fingers between the lever and bars makes finding neutral tricky. Using the short lever helps, then it’s just 1 finger right at end next to the ball.

Thanks Konrad, a gold mine of information. Maybe this job isn’t as bad as I initially thought….

Is it that simple? To be honest I don’t have a clue. Is it the ECU and injector which controls the demand and supply of fuel? Does the pump just pump at a constant rate regardless of throttle input?

Firstly the cylinder head had a full overhaul, the exhaust valves were very lipped, intakes not so bad. The valve guides were still well within spec so they’ll do another 20 years. The small end of the con rod was showing wear, which was giving me a slight knock when flat out. The big end, piston and cylinder were surprisingly good with the piston rings taking most of the wear. The top ring had lost almost 1/3 of it originally circumference! The bike is finally going back together and it’s been put on a diet to shed a few pounds whilst everything has been apart. ( I’m not getting any younger, bike time is limited and a few kg’s saved will help a lot… in my head at least). My next port of call is to tackle the fuel tank and get rid of the hefty steel fuel pump set up. I’m aiming on using the pump from the 260’s which is readily available from the NSF250R race bike, the injector mount to take the new pump will need modifying and a new hose will need to be made up. I’m pretty sure all the models use the same injector. I have a spare injector set up which can be a donor if needed. What I don’t know though is if my ECU will be able to communicate or can be made to communicate with the new pump. I have the Programmable HRC ECU from the early bikes. Has anyone done or tried this before? I can’t find any information anywhere.

The tensioner arm returns back into the swinging arm and the bolt threads in to it. There are a couple of copper bushes pressed into the swinging arm which the tensioner pivots on. They’ll probably be worn as will the aluminium tensioner.

After a bit of time on the google, I found Ben Coyle Racing for the head and crank jobs. He was familiar with the 4rt and knowledge about trials. After a quick phone call, gas flowing was ruled out as the process moves power around. What you gain in one area you lose in another, but a head clean up and polish would help things. The valve guides wouldn’t be a problem either as they custom make them for race engines. I’ve nearly all the parts gathered up, just the con rod and big end to decide on. The dogs dangles of rods is the CP Carrillo at around £280, but they don’t supply the crank pin, bearing or washers. So another manufacturer needs to be considered for those. In my mind, it appears to be pointless to put best rod in and then have to compromise on the pin and bearing. The next best option seems to be Wossner or Pro X for the complete kit at £120ish

There is a yellow connector under the tank. This joins the looms together. You need to remove the correct pins from the yellow connector to remove the lighting wires. This also puts the ECU into the correct setting for competition use

My well used and abused 2006 bike is ready for full engine rebuild. Con rod, piston, cylinder, cam chain and head work. The con rod is straight from a CRF 250 and will have to be aftermarket as a genuine Honda part is only available as a full crank set ££££ The piston, cylinder etc are fairly straight forward, but I’ve never delved in to a cylinder head. I’m presuming valves will be need to be replaced and the seats re cutting and profiling which I will be getting someone else to do as I don’t have the tools to do them, whilst the head is off and stripped I thought I’d get it gas flowed. Anyone have any thoughts or experience with this? After reading the service manual, the valve stem and valve guides need measuring together and against new valves (which I have) to determine whether new valve guides are needed. These valve guides DON’T exist in the parts list or drawings. Any thoughts on this? The cylinder head, cam, valves and everything in between have not changed from the original 2005 250 engine right through to the current 301. I was surprised by that too, and again the valve guides don’t exist in any parts diagrams. Again, has anyone had any experience on cylinder head work on bikes in general and any thoughts on the allusive valve guides? Thanks