xr250 engine issue

[Jason T]

I have recently bought an XLR250, but I believe the engine is the same as the XR250 so thought it would be better to ask the question here
Since I bought it the engine has made a slight ticking/rattle noise which I assumed was either valve adjustment or cam chain.
I have adjusted the valves with no effect so I decided it must be the cam chain.
Today I took the cam cover off and inspected the chain, which appears to be tight. Below is a picture of the chain tensioner which looks to me as if there is still plenty of wear left in the chain?



So I started to look at the other components and found my cam followers to be in what I consider to be a poor condition.
Below is a pic of the worst one:



I assume that these should be smooth on the part that follows the cam?
Three of them are slightly rough and the one pictured has a noticeable ridge in the middle.
Could this have caused the noise I was hearing?
From looking at the picture do I need to replace the followers? I assume that I will have to
If the followers are replaced should I fit a new cam as well? I can't see any actual wear on the cam but as they run together should they be changed at the same time?

Thanks for any help/advice

Jason

[AlanH]

Certainly replace those followers.

Check out the cam very carefully for surface wear and marks. Often it is just the followers that go but if there is any sign of pitting on the cam surface, it'll eat the new followers. You can get a cam repaired by a specialist.

Check in the manual for the amount of tensioner wedge that should be showing as that is the camchain wear indicator. It looks borderline replacement time to me.

[Jason T]

Thanks for the reply
- I'm waiting for my manual to arrive, but couldn't wait to get started on the engine! As far as I know the wear on the chain is measured by how far in the wedge on the left of the tensioner is? The trouble is I'm unsure how far out it will be with a new chain! Does anyone have a pic of a tensioner after the chain has been replaced? If not I'll just wait for the manual to come
- I assumed the followers were worn out so have been looking into prices for a new cam and followers and this is what I have found......
- Genuine Honda cam and followers are $334 or approx £200.
- I've found this aftermarket cam and followers on US ebay: ARM VALVE ROCKER + CAMSHAFT HONDA XR250 XR250L XR250R :eBay Motors (item 140342688744 end time Sep-05-09 07:25:30 PDT)
These are $130 or approx £79.
- The other option is to find some good 2nd hand parts over here.
So out of the above three options what would you go for?

Thanks for the help

Jason

[AlanH]

The wedge on the right moves out (up) as the chain wears. The wear limit is given as the maximum allowed measurement of the exposed wedge. Any further out than the limit and it needs replacement. That one looks a fair way out. On Dommies, it's only one or two mm out on a new chain - similar with an AT.

If the cam's okay, I'd just buy the Honda followers. If the cam's shot too, that eBay listing looks promising. Add the VAT, shipping and Duty onto that price and the £79 becomes more like £130. For another £70 you'd be getting Honda Genuine. Good second hand parts are rare 'cos the followers are a weak point on these motors.

[AIRWOLF]

As Alan says the followers are shot. . . . . the xlr and xr are basically the same, but i would check on part numbers for compatibility.

[Jason T]

The £200 for the Honda parts was off the bike bandit website in america, so that would be plus shipping and taxes etc.
My local Honda dealer was open so I nipped in to see if they listed the parts.
They had nothing for the XLR but had the equivalent year of XR 250 listed.
They want £236 for a cam and 4 followers including the vat. I was surprised at that as Bike Bandit normally works out cheaper even with the postage. I will need to double check the compatibility between the XR and XLR before spending that much!

I will take the cam out and double check its condition, on first inspection it seemed okay but I don't want to spend £100 on followers just to wreck them!
I assume any scratches or marks on the lobes mean that the cam is scrap?

I'm waiting for a postage quote on the after market parts from america, but it looks like it will be approx £100 more for Honda parts.

So I'm in two minds now about what to do. The Honda parts have only managed 12k KM before failing, how much worse can the after market ones be?

I may as well change the chain while I'm doing all this, so I will get one of those oredered anyway.

hmmmmmm, much to think about!

Jason

[Jason T]

I forgot to mention that while serching the web about cam chains I found this pic of a tensioner on a very worn chain! But as I said above I will change mine anyway.

http://www.cornhuskermotor.com/OldSc.../tensioner.jpg


Jason

[AlanH]

Post some photos of the cam lobes. You may not need to buy a cam which is the most expensive part.

I had an XBR500 that knocked out a set of followers in under 10k miles. The replacement followers lasted a further 90k miles with the original cam before the engine went off bang. I think the previous owner either ran it low on oil or did lots of really short trips.

[Jason T]

I've taken the cam out today, and now I'm certain I will need a new one.
Below are some pics of the lobes:





The pics don't show it that well, but there is a big lip at the edge of three of them

So a new cam is going on the growing list of parts, but I may have found another problem as well!
The cam has bearings at either end that are in good order. The middle of the cam runs in the aluminium of the head and doesn't look very good!
Below is a pic of the head:

There are some grooves in the aluminium, but the cam turned freely enough in it.
Does this centre 'bearing' do much or is the majority of the load carried on the bearings at either end?
Will the bike run okay if I fit a new cam, or do I need to start looking for a new head?
I'm going to stop taking parts off now before I find more expensive parts that need changing!

Jason

[AlanH]

Hmm. That's not looking too clever. Often you can get away with just the new cam but it depends how bad the wear is. Wait 'til you get the manual and check against the wear limit specs.

The head can be phosphor bronze bushed rather than scrapping it. The head has to come off at which point you should check very carefully for cracks between the spark plug hole and valve seats - yes another common issue. If it's cracked, see if you can track down a used head. Repairing cracks is often unsuccessful but hopefully someone here can recommend a good engineer if that turns out to be the case.

You could always go the low cost route and order that cam and followers from the US, bung it all back together with a new camchain and run it 'til it goes bang - which may actually be a long while with regular oil changes as these will run in a hell of a state.