A forum for owners of Yamaha TTR250 trail and enduro bikes!

zipper · Member

Top end rebuild - stock TTR

mossproof · Super Guru

Great colour scheme. Much nicer than the pale blue frame with purple wheels! Neat looking bash plate too.

ttr steve · Super Guru

I second that!

zipper · Member

Thank u.

So i managed to build a rear rack and headed southern Portugal for 3 days. 1100kms, part of the TET and Transalgarve.

First 80kms were offroad before Sunrise. Nice experience!

So when i left home i had a leaking cilinder base gasket. In the end of the trip i had about 300ml oil burn or leaking.

zipper · Member

So i decided to replace the cilinder gasket.

zipper · Member

Found out a lose carb boot, piston rings worn out, and piston clearance too big ( i noticed some piston slap on low rev range). The valves are not seating properly and not sealing, piston crown and head full of carbon. Spark plug with a shiny oily look.

zipper · Member

Also found some ring scoring on top and bottom of cylinder.

Ordered new valve seals and a a 0.5 new piston to replace. Will rebore cylinder,refurbish valve seats and seals and remove all the carbon build up.

I found out these 2 marks on cylinder and head? Are these factory marks??? Doesnt look like....

TTRfan · Super Guru

Hi Carlos!

There are numbers scratched into the TTR casings but I don't know what they represent. I am 99% sure yours are factory markings smile

Brian

zipper · Member

Ok. Good to know. They look handgraved.

zipper · Member

Hi.

Reinstalled a rebored cylinder with a new piston, and the valves were lapped. New valve seals also.

At the machining shop they checked valve clearance after valve lapping and adjusted. In my opinionbthey are too tight.

This is what i got after installation

Exhaust left 0.20-0.25
Exhaust right 0.15-0.20

Intake left 0.05-0.10
Intake right 0.05- 0.10

Strangely i got a loud ticking when i rev the engine. Plenty of oil on the head, timing is correct. You can hear it after 1:00 on the video.

Any opinions?

youtu.be/iwpa7Gyij5M

zipper · Member

Some pics just to make sure everything is ok.

zipper · Member

Tdc

zipper · Member

No ideas what can cause that loud ticking? Can too tight valves be the cause?

TTRfan · Super Guru

You got the camshafts positioned spot on.

A loud tick is usually a loose valve clearance. I tend to adjust the exhaust valves at the lower end of the clearance specification as they seem to be the usual noisy culprits.

Could anything have got into the combustion chamber on the rebuild? Does the tick turn into more of a rattle when you rev the engine? Don't ask how I know that noise disbelief

ttboof · Super Guru

Good advice Brian it's quite a rattle in the Clip doesn't sound like a tapet tick. Is there a chance the Cam chain tension is questionable.

Just another check is the header pipe tight In the muffler joint. Is the heat shield tight on the header

Probably not the cause but just check

A screw driver with your thumb on the top of the handle then press it on the motor with your thumb against your ear and you have a crude stethoscope sometimes it can help narrow down the noise.

-- Edited by ttboof on Tuesday 15th of January 2019 09:08:19 AM

zipper · Member

The valves are already on tight side....i was thinking maybe too much...almost seems like the valves slightly hitting the piston!!

About something inside the combustion chamber seems unlikely...unless it was trapped in the valves from the machine shop...very unlikely.

I have a friend with a ttr600 and the noise seems almost identical. What is strange is that before i took it apart was a quiet engine

zipper · Member

The noise is clearly coming from the head...it does look a bit like a rattle...but like a valve very loose...wich they are not.

Cam chain tension is ok. Not loose.

I just noticed in the workshop manual they mention to turn the engine clockwise...shouldnt be conterclockwise??

-- Edited by zipper on Tuesday 15th of January 2019 04:48:17 PM

TTRfan · Super Guru

cylinder head.jpg cam chain and valve gear.jpg

OK. Having identified that the noise is definitely coming from the head, what are the possibilities?

Just brainstorming now:

Diagram 1:

Camshaft caps - cracked or loose ?

Diagram 2:

Cam buckets - could one be cracked or damaged?

Collets - could one be loose - unlikely - probably not possible because it would prevent the shim seating

Shims - can't think how they could cause the tapping and, in any case, are unlikely to be damaged

Valve springs and seats - could a part be damaged - unlikely

Diagram 3:

Cam shafts - very unlikely that they would be damaged in such a way as to cause the noise

Slippers - could either one be damaged in such a way as to cause ticking? Can't think how.

Cam chain tensioner - again, I can't think how it could be damaged in such a way as to cause a ticking noise

Of all the possibilities the cam bucket/camshaft interface seems the most likely culprit.

This is assuming that (a) there isn't anything loose in the combustion chamber, (b) the rings were fitted properly and not causing any issues and (c) the little end was checked before the rebuild and that wasn't worn.

zipper · Member

Thanks Brian.

Answers:

Cam caps tight and good shape.
Cam buckets : check

Collets, valve springs, seats and shims: check

Cams: check
Slippers and cam tensioner: check

Conrod small end was ok: little to no play

Piston rings: gap was ok, the "N" mark up, and the end gaps on a cross patern

Something in the combustions chamber: i was trying not to, but i think i will have to take everything apart again. That wat i can also check valve to piston clearance

-- Edited by zipper on Tuesday 15th of January 2019 08:41:37 PM

TTRfan · Super Guru

No need to take the head off to look inside - buy or borrow an endoscope - cheaper than a new head gasket and you can use it for other purposes - see https://www.ebay.co.uk/sch/i.html?_nkw=endoscope&ul_noapp=true

I am 99.9% sure that even if you had no valve clearances at all the valves wouldn't touch the piston wink

To reassure yourself, the endoscope would be able to check the top of the piston for any giveaway marks.

Brian

zipper · Member

Too late :)

Combustion chamber clear...just ordered shims and a brand new head gasket kit from Totally TTRS

-- Edited by zipper on Tuesday 15th of January 2019 11:14:58 PM

TTRfan · Super Guru

You work at the speed of light!

Well, at least now you know it's all OK in there so it won't niggle away at you as it would if you hadn't taken the head off wink

So, it's got to be valve clearances????? Nothing else left to blame????

zipper · Member

At least i can not find anything wrong.

leigh · Senior Member

Did something similar with mine recently.

Re shimmed the valves, exhaust were at about .14 and I changed to .24 - sounded ok at idle, but ticked very loud at more revs and when it got warmed up. Reshimmed to .19 and noise is gone (just a hint of a tick)

p.s. that was my third go at setting them :) first time was around .28 I think - and yep, at idle that was effing noisy.

Listened to the video and mine was more of a tick than that - but it surely must be the issue

Cheers Leigh.

zipper · Member

Thanks Leigh! Will keep that in mind!

zipper · Member

Got my parts today! Thank Steve and Lisa

ttr steve · Super Guru

Always happy to help, stickers will look good on your bike smile

Steve

mossproof · Super Guru

Good luck with the (second) rebuild.
I'd love to see more pictures of your trip - I think the Spanish TET gets a lot of coverage but we see less from the Portugal sections, maybe just because it is closer to the ferry ports for UK riders.

zipper · Member

I will post some pics later. For now i got to this point. All assembled and properly torqued.

-- Edited by zipper on Friday 25th of January 2019 01:30:26 PM

Dan-in-a-Van · Veteran Member

If the latest parts don't fix it. I had an old Super Dream engine that clicked after a previous rebuild. It finally turned out to be a slightly bent valve stem. The valve was sticking as the cam pushed it down and then clicking back up as the piston came up.

zipper · Member

Hi.

Everything reassembled and this is what i got.

Still ticking a bit on 1st startup, but i ride it to comute and after a few kms got quieter. Not as it was before rebuild but i will wait for break in period and see how it ends.

Thanks for the help.

https://youtu.be/2e8z8olCIJI

zipper · Member

Hello again.

After break on, i got some fresh new oil on it. The oil on it had some kms, and whrn i drained it i found out i had 1,4lts inside the engine.

I added some oil before last ride and i was sure it was not above top level on sight glass.

So now i bought 1lt of oil,, got.it inside the engine, and the oil level is right next to minimum on sight glass. Is it supposed to be like that? 1lt= minimum level??

This is oil mark when bike is levelled.

-- Edited by zipper on Thursday 28th of February 2019 07:22:19 PM

ttboof · Super Guru

Hi

1.4l is prob enough to have the bottom of the piston close to splashing in the oil if not the crank would be doing a bit of extra swimming .(may make a bit of Noise but would also slow things down a bit due to the extra work moving the excess oil about )

My TTR is a blue one the full mark standing straight up takes 1100ml . so id say the 1litre to the bottom mark sounds about right just add a little until you hit the top mark .

run it a little while to warm up turn it off and stand it upright and the oil level should be between the lines .

greekmountains · Veteran Member

zipper wrote:
Hi.

Everything reassembled and this is what i got.
Still ticking a bit on 1st startup, but i ride it to comute and after a few kms got quieter. Not as it was before rebuild but i will wait for break in period and see how it ends.

Thanks for the help.

https://youtu.be/2e8z8olCIJI

hi my xr does this sometimes apparantley its the cam chain tensioner which may or may not look ok but is defective in some way(not taken apart as it just keeps running..)