help cold starting a vtr 1000

[sebjones92]

Hi guys...bit of a different post for you, I have a home built off road buggy/go kart with a vtr 1000 in it. I'm told the engine year is between 2000 and 06 ish, but only have the engine number which I'm told you can't identify the year of the engine from.

So basically I've only used it a couple of times since owning, had to do some upgrades to rear suspension and driveshafts etc before I looked at the engine. Since I bought it it always 'struggled' starting from cold, when I say struggled, just look a few cranks and half throttle wish for a couple of mins to get it warmed up, once warm it runs fine and starts after only a couple of cranks. Now its not been ran for a few weeks I've put everything back together (no-one of the engine components came off) and I can't get it to fire up.

Just wondering if there are obvious first signs to check...oh yeah one question - will the neutral switch stop the engine starting? I snapped the cable while changing the oil filter due to the awkward mounting on the buggy, from bike I have owned in the past the neutral switch actually stops the engine cranking over rather than just let it turn over and not start (like a killswitch normally does) but maybe I'm wrong - which should mean an easy fix I just need to repair the cable? Other than that...fuel is getting out the bottom of the carbs, I have a spark at both cylinders although one seems weaker than the other - but a spark none the less? Just need to check the compression.

Would appreciate any other thoughts - you guys know this engine a lot better than I do.

Thanks

Seb

[sebjones92]

Ok so should have done the compression test before posting sorry...

dry test cylinder 1 (front) 50psi
wet test cylinder 1 150psi
dry test cylinder 2 - 0psi
wet test cylinder 2 - 20psi

I can actually see the oil from wet test leak out between the top end cylinder and bottom end when turning over (only on cylinder 2)

will make some room in the garage to start stripping it down, i'm guessing piston, rings...hopefully valves are ok, we'll have to see

cheers

[Watty]

Front cylinder cct failure and bent valves!! Or head gasket?

[sebjones92]

cct failure common on these engines? I guess if thats the case theres a high chance of bent valves...probably wombles piston too but I'll give you an update tomorrow once i've pulled it apart

[AMCQ46]

Cyl 2 is totally fecked, and cyl 1 needs new rings or valve seats cutting in.

You should be looking for about 150psi dry.

And welcome to the forum, buggy sounds nuts

[alanfjones1411]

Welcome to the forum mr Jones (another one.We are more common than teal)Buggy sounds like it will be s right good fun once sorted.These fella's will put you on the right track.

[sebjones92]

well a bit of a surprise so far...I expected some obvious signs pretty early on due to the low compression results...I started with cylinder 2 as it was the worst, so far haven't found any obvious signs of damage, the chain tensioner was fine, removed all valves which look ok to me, not obviously bent, and the faces don't look damaged, theres a fair bit of carbon build up on the exhaust side as to be expected, and a little on the intake. I'm no expert at what to look for when it comes to valves and seating etc so I've taken a few photos, hopefully you guys will pick up on something! as far as the cylinder heads, no cracks or warping, tested with a straight edge and feeler gauge all seems perfect, all valves sit really tight in the head with minuscule if not zero play/sideways movement.

I was expecting a problem in the head especially in cylinder 2 - maybe it is just the piston/rings and head gasket? which would explain the oil seepage between the gasket when compression testing? but again the gasket wasn't split, didn't look damaged to me.

anyway, pics say a thousand words :big grin she's gonna be pic heavy...

cylinder 1....






















and cylinder 2....























not really looking forward to removing the transmission and crankshaft to get to the pistons! my yamaha dirt bike was much easier with a separate cylinder between the crank and top end!

[sebjones92]

ah sh1t, am I right in thinking the engine HAS to be removed to replace the pistons? Do the transmission linkage bearings sit on the 'upper' crankcase, so piston replacements are effectively done with the engine sat up side down? or have I got it mixed up.

hopefully I can get it done without removing the engine as its going to be a pig of a job, didn't actually realise how much of the engine has to be stripped to get to the pistons.

cheers guys

[AMCQ46]

Tony mon will be along soon, but I am pretty sure you can get the big end bolts through the sump and pull the piston and rod out the top

[kenmoore]

Search for high compression pistons on here.

That will explain how to do it through the sump.

Make sure you replace the rod bolts.

Much easier than stripping the whole engine!

[sebjones92]

will do cheers.

Do you think the piston and rings could be the sole reason for zero compression in the rear cylinder? maybe as well as the head gasket which obviously I'll replace when putting back together? Just a thought as I always thought the rings would only allow some blow by and reduce the compression but not make it as low as it is?

Guess it will be worth getting the valve seats ground while the heads are off.

[tony.mon]

Hi.
Yes, you can just remove the sump and get to the big end bolts that way.
It's easier to remove the oil pump first- that gives you more room to work - but you have to pull the clutch off in order to get the pump off.
You should be able to see a nice clean ring of bright metal Al around the seats and valve heads, it's not easy to tell but from the pics that doesn't look like the case with yours.
And you need to check piston to bore clearance.
Any marks in the bore indicating ring problems?
It could just be a sticky valve stem holding a valve slightly open.
The exhaust valves should have a dry finish, carbon, maybe but dry.
Yours look like baked on oil, which has a shiny finish.
One-way or another, if that's the case it's burning oilsomehow.

[sebjones92]

cheers tony.mom,

the intake valves mostly have shiny seats and heads, still not perfect but look pretty good, but yes the exhaust valves on both cylinders don't have this. so would you recommend replacing the valve stems to get a 'better' seat, as well as getting them ground?

as for the oil, yes there was a couple of exhaust valves like this I'm hoping it was just from doing a wet compression test, maybe used a tad too much oil.

Will work on removing the engine tomorrow anyhow and see how I get on.

[tony.mon]

No, valves clean up well enough with a wire brush in a drill, as long as they drop through the guides under their own weight when slid into place (without springs, obviously) they'll be fine.
You shouldn't be able to feel any side-to-side movement in the guides.
Check piston-to-bore clearance.

And, yes, i'd missed that you'd done a wet test- that probably accounts for the shiny residue.

Valve stem seals can allow lots of oil onto the valve heads as well- if you have the heads off it's always worth putting anew set on, but use genuine ones- I've had problems with pattern seals in the past.

[sebjones92]

Sweet I'll give them a clean up and check how the sit in the seats then.

Piston to bore clearance, both pretty much at 0.18mm, I see they should be closer to 0.06 is that correct? at 0.15 there is no resistance at all, 0.18 both have a little resistance. So looks like two worn pistons and rings?

The cylinders at the top are both at 98.01mm. don't have a calliper tool to measure the centre and bottom of the cylinder but will try and suss one out.

engine will be coming out in the morning, not so simple they way the engine mounts have been made on the buggy doesn't leave much room for manoeuvre!

cheers guys