Bugger it! I've got problems with my VT250 :(

[GeorgeR]

Gidday people - hope everyone has had a better day than myself. What started off as a nice Monday afternoon ride ended up with me nursing my poor old VT250 home with a rather odd noise emanating from the engine :(

About 30mins into my ride I was coming up to a corner, backed off the throttle and noticed a strange change in engine note. I coasted through the corner and on applying the throttle again was greeted with the extremely unpleasant noise of a knocking/clacking sound. Hmmm I thought - this is not a healthy noise at all. I went up and down through a few gears to eliminate the drivetrain as the problem before pulling over to take a look. Nothing was obvious from the outside (I didn't really think it would be) and since it seemed to be running alright apart from the noise I decided to nurse it slowly home. Things were the same all the way back - I noticed however that the noise was really only apparent on constant throttle. Any acceleration or deceleration and the noise was much less noticeable.

The noise sounds like something is loose or rattling - it's most apparent at ~5000rpm when free-revving it but you can hear it when blipping the throttle at lower rpm. There is no apparent noise at idle. I'm thinking it could be a valvetrain issue, perhaps a crook valve or something similar. It could be a big-end problem, but I really hope it isn't.

I know how hard it is to diagnose problems without hearing/seeing things - but does anyone have any ideas as to a likely problem? I have no qualms about stripping the engine down if necessary - I'm just looking for a bit of a direction from someone more experienced than myself (I've rebuilt a couple of car engines, but have no experience with bikes). Any help would be much appreciated - no bike is no fun :crybaby:

Oh, almost forgot, my bike is an '86 VT250FG. 20,000km on the clock. I gave it new oil and coolant ~1000kms ago - levels of both are still fine.

Cheers.

[Bonez]

Loose alternator rotor maybe.

[Posh Tourer :P]

sounds like a bearing collapsed somewhere maybe...

[jrandom]

Hydrocillator.

[Motu]

Sounds like a big end or piston to me,it will make more noise when unloaded like running free at 5000rpm or reving from idle to bring it under load.Applying load on the road will sometimes make it stop,the excess clearance is taken up with the loading and the noise goes.A piston would more likely bring on smoke or a low compression and poor running.I'd say you've done the bottom end in,check that oil level again.Bummer,this is not good news - go and do something you enjoy to ease the pain....and stay away from the motorway and trucks...

Oh yeah,and the alt rotor - I've seen engines rebuilt because of a loose rotor or crank pulley.

[Blakamin]

Oh yeah,and the alt rotor - I've seen engines rebuilt because of a loose rotor or crank pulley.
I saw a bike sold coz the owners thought it had seized... was the kick-start spring had moved and jammed 2 cogs!
Glad I paid $80 for that cb360.. was mint!

[F5 Dave]

A bike with well documented camchain tensioner issues. Sounds like it backed off & has stopped working efficiently. 5000rpm is very likely the revs you would hear it at.

If it dies it will destroy the engine.

[GeorgeR]

Sounds like a big end or piston to me,it will make more noise when unloaded like running free at 5000rpm or reving from idle to bring it under load.Applying load on the road will sometimes make it stop,the excess clearance is taken up with the loading and the noise goes.A piston would more likely bring on smoke or a low compression and poor running.I'd say you've done the bottom end in,check that oil level again.

Hmmm, that was my first gut instinct too - I was hoping noone else was going to agree :(


Bummer,this is not good news - go and do something you enjoy to ease the pain....and stay away from the motorway and trucks...

I got nice and drunk last night (being the end of uni and all) - that eased the pain temporarily. The dawn of a new day however means I have to face the problem. It couldn't be a worse time to happen either - just when I'm going to start really needing it. I guess I can get my cage back on the road - provide a bit of temporary transport - grrrrrrrrrrrrrr :mad:

[GeorgeR]

A bike with well documented camchain tensioner issues. Sounds like it backed off & has stopped working efficiently. 5000rpm is very likely the revs you would hear it at.

If it dies it will destroy the engine.

That was also a thought that came to mind - it doesn't really sound like a chain rattling around, but I suppose it could be causing secondary issues? I was going to take a look at that end first anyway - just in case I'm "lucky".

[GeorgeR]

Hydrocillator.

Oh, and just in case anyone else was wondering what the hell a hydrocillator is (and why you haven't heard of one before): http://66.34.10.12/AAAS/hydrocillator.htm :killingme

[wari]

WEll GEorge ...

THe hydrocillator is little known in the publick domaine ..

YEtt well knowne device onthis board ... :sunny:

WE're here to hellp and en-hance your know-ledge of the mechananiacal ..

YEsiree BObbb .. :spudwave:

[Jase W]

They could have done a better job of photoshopping Mortimer Ford's picture into that assembly line photo. I wonder who would actually believe this?

[Posh Tourer :P]

"Should this offer be ignored, the NTSB will conduct extensive investigations of any offending manufacturer, and pending the discovery of further non-compliance, will face revocation of ALL rights to continue business in the Untied States"

Thats a pretty severe warning. Still, maybe better the devil you can recognize than the devil you cant

[Sniper]

A bike with well documented camchain tensioner issues. Sounds like it backed off & has stopped working efficiently. 5000rpm is very likely the revs you would hear it at.

If it dies it will destroy the engine.

I tend to agree with Dave on this one.

Might pay to have a quick look.
I dont actually think it cost alot to have it done either, just not in Blenheim where the tend to charge labour, labour for labouring, thinking of labouring, lunch, thinking, going to work, going home from work and just being total arseholes

Get him :kick:

[F5 Dave]

I tend to agree with Dave on this one.

Might pay to have a quick look.
I dont actually think it cost alot to have it done either, just not in Blenheim where the tend to charge labour, labour for labouring, thinking of labouring, lunch, thinking, going to work, . . .




Hmm, thinking about lunch.[Drool]

[Motu]

I've found camchains make their worst noise at idle and smooth out as the revs get up,but if a chain get too worn the inlet valves can start clipping pistons.I know nothing about these engines at all - apart than it's a Honda,which have strong bottom ends and weak chains,but don't get led into asumptions.

[aff-man]

Same thing happened to my vt250. I had apparently bent the crank shaft due to a fucked piston apparently. $1000 later i had replaced the engine. :crybaby: :crybaby: Hopefully it's not that for you :gob:

[GeorgeR]

Cheers for the ideas guys - much appreciated. I think I'll strip it down a bit this afternoon and see what I can see.