Which seal did he replace? I am not familiar with DTR's but, in some bikes, the left seal can be changed without stripping the engine but the right seal cannot.

It can cause barrel damage if it seized and that normally means a rebore, new pistons and rings at the least.

In case you don't know what I am talking about, here is a left seal change on one of my bikes.

Left hand side of the engine with the crank and knackered seal showing.

Seal removed and you can see the crank bearings exposed

New seal fitted

I can't quite remember what he told my dad. He did say he's going to have a look at it when he's back cause he's noticed it sounds loud and I completely agree with him there. Hopefully nothing too serious I was on it today and it did get into speed onto e national speed limit but was quite slow getting there.

Does a seize mean it won't start at all, or can it seize for a short while then work again but slightly faulty? If so i think it may have done that when the first incident happened.

Aye newman" is the new seal in oppisite way round from old seal. i see groove and spring in third photo, i tried to magnify to see ,

Aye smithy" the term is "partial seizure" so musta been hot [air leak] , or lack of lube

Ahh okay well thanks a lot for all of your help, it's running fine and idling nicely apart from it being a little loud.

Loud" is it not standard exhaust ? if baffle is missing , this reduces backpressure , = loss of BHP

Aye newman" is the new seal in oppisite way round from old seal. i see groove and spring in third photo, i tried to magnify to see ,

No spring in that side John.

Sorry to bring this back up but now after sitting for a few days, the bike is leaking petrol out of the float bowl overflow tube thingy whenever the fuel is set to on or reserve. It will leak whether the bike is vertical or on the side stand irregardless. I did have it running for about ten minutes, turned it off went to get my gear on and noticed a pool of petrol, it isn't just a small leak it's literally streaming out. :/

Is it coming form one of the overflow pipes? If so then you have probably got some grit in your float valve. Inside the carb there will be a valve that stops the flow of fuel when the floats reach a certain height. Floats can leak and cause the same effect and also this can happen when the float level is incorrectly set. Normally it is just some grit causing the valve to not seat properly.

You need to take the carb off, take the bottom bowel off, take the floats out and clean the valve and any sediment i the bowel. When you put it back together reset the float height.

Guess I'm waiting for the mechanic then since my dad won't let me touch the carburettor even though it's my bike haha, I have to learn some day! Thanks for the quick reply though I'd assumed it would be something like that just annoying I can probably fix it myself but can't!

It is not a big job. You normally only need one cross head screwdriver and an hour.

You undo the 2 jubilee clips that hold the carb onto the engine and airbox (one each side of the carb. Unscrew the top cap of the carb. Take the carb off the bike, turn upside down and remove the 4 screws. Take the bowel off and the floats and valve are exposed. Push the pin out that holds the float in, take out the floats and you will see the valve, pull out and clean it and the brass fitting it sits in. Put the clean valve back in and refit the floats and pin, check the float height and then do all the rest in reverse order to refit the carb.

A good DIY job to start with.