XR400 Seized/Blown Engine Need Rebuild Advice

[Orujo]

Hi All, thanks for taking the time to comment. Yeah 12,000 km should be low millage but putting it all together it might make sense that it was used and abused offroad, then clocked and sold on.
The seller appeared to be on the ball with the maintanence of the bike and assured me it just had an oil and filter change. I checked the oil level a week ago and it seemed fine. But who news.
As I said, Ive only had the bike less than two weeks and didnt see the need for an oil change so soon. Also, I didnt think 80 kph was too fast as the seller said he'd changed the rear sprocket for more top-end and it should be good for 100 kph.

The knocking noise I heard appeared to be comming from the left side of the engine, would this indicate it was a issue with the cam chain? Could this be the seized item?

Jasonbc, you sound like you've been through the wars with your engine. I have no intention of going fore a bore out, just get it back to stock. Can i assume from what you said that £400 would be my worst case or upper limit for parts costs? If you are able to dig out the full list of these parts that would be great. Also maybe a link to where the parts were sourced.

As for the the breather tube, I think the workshop manual mentions something about it just being strapped to the frame.

[Esoteric1]

Yeah sounds like you got ripped, hope you didn't pay too much for it.
They worth it though, a bit of hard work and maybe £500 and you will have a very good life long bike.
I would take out the engine, take the cylinder head off as well as all the other bits and just give the crank case to a bike mechanic to change the big end bearing and all other bearings. You can change the small end bearing, piston kit, cam and rockers if they are worn.
Giving the bike to a mechanic to do the lot your looking at £800. You can half this price by doing stuff your self.
Knocking indicates the big end bearing has gone, mine seems to knock a little loader when the engine is warm too. Strange one that! Engines normally get quieter as they warm. But then these are not normal engines.

The breather pipe is connected to the air box, and the other end just hangs loose towards the floor.

[jasonbc]

Hi All, thanks for taking the time to comment. Yeah 12,000 km should be low millage but putting it all together it might make sense that it was used and abused offroad, then clocked and sold on.
The seller appeared to be on the ball with the maintanence of the bike and assured me it just had an oil and filter change. I checked the oil level a week ago and it seemed fine. But who news.
As I said, Ive only had the bike less than two weeks and didnt see the need for an oil change so soon. Also, I didnt think 80 kph was too fast as the seller said he'd changed the rear sprocket for more top-end and it should be good for 100 kph.

The knocking noise I heard appeared to be comming from the left side of the engine, would this indicate it was a issue with the cam chain? Could this be the seized item?

Jasonbc, you sound like you've been through the wars with your engine. I have no intention of going fore a bore out, just get it back to stock. Can i assume from what you said that £400 would be my worst case or upper limit for parts costs? If you are able to dig out the full list of these parts that would be great. Also maybe a link to where the parts were sourced.

As for the the breather tube, I think the workshop manual mentions something about it just being strapped to the frame.

Here goes prepare to shock your self. CAm chain and tensioner are on the righthand side of the bike as you sit on it. When mine went Honda couldn'/ wouldn't supply a conrod you had to buy a complete crank assembly at £550 so that idea went out the window got a conrod from offroad only.



This was the one job i couldn't do at home took it to a enginnering workshop to be dti'd and pressed and the bearings wired in. This was a slow process as the crank pin had heat treated itself and the pin couldn't be pressed out. It spend 14 hours on the spark erroder having a hole put through it so the pin could be pressed out once that was done it was a really quick job to wire the bearings and dti the rod.



Unfortunatly my bike had a 440cc kit on so needed a new liner, barrell. Not until i bought a new cylinder did i find out a local engineer supply and fits liners for around £80 + vat.

All the honda stuff I had from david silver on the 3-4 week wait as the price is normally 1/2 - 1/3 cheaper than next day or over the counter price..





Hope that scares you a bit, i didn't think it was that much until i dug out the paperwork

[jasonbc]

[QUOTE=Esoteric1;492649]They worth it though, a bit of hard work and maybe £500 and you will have a very good life long bike.
big end bearing and all other bearings. You can change the small end bearing, piston kit, cam and rockers if they are worn.
Giving the bike to a mechanic to do the lot your looking at £800. You can half this price by doing stuff your self.
Knocking indicates the big end bearing has gone, mine seems to knock a little loader when the engine is warm too. Strange one that! Engines normally get quieter as they warm. But then these are not normal engines.

The breather pipe is connected to the air box, and the other end just hangs loose towards the floor.
UOTE]

The don't have small end bearings, it a bush through the rod small end and the knocking can be anything, if you've ever ridden a XR you will know how many different rattles, bang and vibraitions they have from different things, not just the motor

[Esoteric1]

OK. Thanks and thanks for the reciepts.
I will make a note of all that, infact I will rob the pictures and save them.
Cheers!

I think having to pay for a new cylinder cost you a lot. You did totally bust your engine big time!

[Pieeyedpiper]

The breather pipe is connected to the air box, and the other end just hangs loose towards the floor.

You sure your breather hose isn't connected to the airbox drain hole?

[Esoteric1]

Yep that's correct.

[Pieeyedpiper]

Yep that's correct.

If you mean yes it is, then you need to disconnect it and re-rout it ASAP. Any goop in the bottom of your airbox will be runnung straight back into your crankcase.
Its not a connection to re-circulate any crankcase vapour, its a drain in case any water enters your airbox.

[416cc]

Talking about strange engine noises, an alloy bashplate seems to reflect all sorts of sounds...some critical...some not so...

And with referance to how long an engine might be expected to last at full chat, I don't think that these engines are designed to be run at full throttle or anywhere near WOT for long periods of time. When I used to race my XR in enduros it was point & squirt & in reality on a rough course it was rarely at full throttle for very long.

[416cc]

If you mean yes it is, then you need to disconnect it and re-rout it ASAP. Any goop in the bottom of your airbox will be runnung straight back into your crankcase.
Its not a connection to re-circulate any crankcase vapour, its a drain in case any water enters your airbox.

My engine breather pipe exits up under the seat & into a push-in K&N filter...


The pipe at the bottom of the airbox should be a pinch-pipe that you operate to dump anything in there down onto the ground/into a tray/onto a rag...