jrsunt

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

I always thought the cracks were caused by neglect and bearing failure, rather than machining defect. The bearings require pressing out on all manufactures and are usually quite tight. The s/arm pivots will weld just fine and as far as stress points go, there can’t be mega forces applied on those pivots or they would have snapped long ago.

Glad you’ve got to the bottom of it. If you’re trying for warranty, it’s not quite the same as going to Mr Lampkin or Mr Birkett and saying there’s a problem as they are the brand and they give a **** about their product. Often at Honda, there isn’t a face, the person you speak to on the other end of a computer is there because it’s a job, they don’t even know what a trials bike is. The dealer will have to submit a warranty claim on the dealer network, it’s a lengthy and tedious job which puts dealers off from doing it in the 1st place. Photos, photos and more photos will have to be submitted. Once this has been done and authorised every single part that needs to be replaced has to be itemised!!!! That is a task alone on this claim. I don’t think you can claim for a full engine without speaking to the factory…. In Spain. It is going to take a lot of time and phone calls from a dealer to get to Mr Lampkin or Mr Birkett at Honda. It is possible. You need the dealer on side as it is a pain in the a*** for them. If you’re not getting anywhere, I may know someone.

As mentioned before, I very much doubt it will need a piston or cam chain unless oil changes have been seriously neglected, they are properly built. The cam chain tensioner is self adjusting and shouldn’t be out of spec at that age, but well worth a look. Checking valve clearances would be an easy one too.

I didn’t mean to name and shame, but have a word with them, a little investigation now could save them a big headache down the road

It does sound a little worrying as the filter is not receiving oil and then not delivering oil to the big end. As far as I know there isn’t a way to test the oil pump. To get to it is an engine out and split job. There is also a reed valve type device before the pump. You could perhaps take the valve covers off and see if oil is getting to the top end whilst it is running, not a quick job on a 4ride though. I’d be trying to get it looked at under warranty, Honda aren’t that bad to deal with if you can get to speak to the right person, an example, of a engine I rebuilt whist at a Honda dealer, a 4ride had been drowned in a river, needed full bottom and top end rebuild managed to get all parts covered on warranty and just paid labour. You’re in a slightly better position as you haven’t fcked up and it sounds like a manufacturing defect. Honda generally want pictures of everything (genuine filter would need fitting) and it gets up loaded onto their dealer network. It’s a pain in the a*** to do but would be worth looking into and it’s not in the Honda mindset to have engines failing. Where did the bike come from?

As Konrad says, in theory it travels from filter to crank. If that wasn’t flowing your engine would be dead. After your dealer visit and 400miles covered, did you drain the oil? Was it discoloured? Was the filter still looking yellow and brand new even though the oil was looking used? It is very common on 1st service 4rt”s to have the original Honda grease on the spring, but the filter and oil would be very discoloured. I’ve done quite a lot of them. I think I have an old generator cover that’s been stripped, If I do I’ll have an investigate.

Like you say, there must be oil circulating in there or it would have expired. I’ve had two experiences and one resulted in a new bottom end due to oil starvation. After damaging the generator cover on a rock the little pencil like raised bit that runs from the filter back into the centre of the crankshaft which is the oil way, I had the cover welded and it blocked the oil way, the con rod was shot in no time. A friend who also had a 4rt thought he had changed his gearbox oil but had drained the engine oil and filled it with gear oil, the bike ran fine pottering around but as soon as you started to push it hard it just wanted to bog down - I presume the gear oil was breaking down under pressure and heat. It is not uncommon for the grease to be on the filter spring and the difference in millilitres between an oil change and an oil and filter change is only 30ml, the filter should have a coating of oil on it but it’s now swimming in it. You may be able to blow down the oil way in the generator cover to see if it frees, I’ve never tried it so it may or may not be open. Hope this helps.

Yeah they’re the same, you’ll struggle to get them from a bearing trader as the size is slightly different from what’s available off the shelf. It’s usually genuine Honda, quite expensive but they last well.

Throttle cable replacement is best with the throttle body off the bike. Since you have a lot of the bike apart, you’re nearly there. Remove the silencer mounting bolt from the air box and the 2x 10mm nuts and 10mm bolt the air box will be almost free. The petrol tank will need lifting too. There is a lot of rubber pipe work running from the cylinder head breather to the air box, all this can be removed. Just blank the hole in the air box and use some of the grey pipe to make a new head breather that runs down the side of the radiator on to the sump guard. A little weight saved and much neater under the petrol tank. Make a note of where the lock nut is on the cable, undo the cable from the throttle body by turning the body. Fit the new cable to the body and tighten the lock nut in the same position as the old one. It takes a little patience in getting the new cable routed under the tank so it does not pull the cable when the steering is turned, particularly to the right

They can get pretty hot, wouldn’t worry about it too much though