One sick little RZ250

[Donor]

So Daisy the mighty RZ250 has had a birthday, and been given two new pistons.

All went so well, I guess we knew something was bound to go arse rapingly wrong, and no surprise at all, it would appear we have not been disappointed.

She won't start from the kick, will run but very raggedly if she is tow-started. There is a frequent belching (chuffing) from the pipes when she does get close to running, and I think we may be looking at a timing issue.

Now, this poses a question - I have read that the YPVS can be timed, but nowhere can I find how the hell this is checked.

So, anybody out there able to suggest a method for having a check, or even give us some more avenues of investigation to look down?

I haven't explained myself very well here probably, so will sit with lappy on my knee in the gargre with baited breath!

Cheers!

[Grumph]

More information needed
was the job done with motor in frame ? how much did you disturb ?
Did you put the pistons in round the right way....
New base & head gaskets ?

[Donor]

More information needed
was the job done with motor in frame ? how much did you disturb ?
Did you put the pistons in round the right way....
New base & head gaskets ?

Job was done motor in place, don't think much was disturbed (well, no more disturbed than me and gijoe1313) - the pistons are definitely round the right way, the base gaskets were hand made (Thank god for lessons taught 20 years ago!) and the head gasket was inspected by a bike mechanic and deemed worthy to go back on.

Everything was torqued to spec (yes, we used a manual... I'll wear the demerits on my man card for that one) and no parts left over. This is where I started worrying to be honest... nothing better than a good luck screw or bolt left over usually

[Grumph]

So rad off,pipes off, carbs off maybe coil off - if I remember it's above the head ?
Well, check the carbs for a stuck float - they tend to get inverted when detatched, and check the coil connections. Has the water level gone down ?
Ignition timing should be untouched. Do the power valves cycle open/shut when the ignition is switched on ? I'd have thought if the PV's were mistimed it would still run clean - just power in the wrong band.

[Maha]

Ok, listen very carefully, I shall say this only wince....go inside and make some cake!

[Donor]

So rad off,pipes off, carbs off maybe coil off - if I remember it's above the head ?
Well, check the carbs for a stuck float - they tend to get inverted when detatched, and check the coil connections. Has the water level gone down ?
Ignition timing should be untouched. Do the power valves cycle open/shut when the ignition is switched on ? I'd have thought if the PV's were mistimed it would still run clean - just power in the wrong band.

Well, on a whim before reading your reply, we had a bit of a dummy spit at the stubborn minx, and with wide open choke and a bit of throttle the bloody thing fired and ROARED.

It rattled a lot more than usual.

Then it stopped, and we can't replicate.

Seems almost like a lack of fuel?

Still chuffing out a cloud from the pipes when kicking her, but was not doing the same when we got her running for a staggering 6 seconds just a short while ago.

We are NOT mechanical wizards, I did my time on cars as a labourer, the other is a teacher of todays youth. I can strip down and rebuild most cars pre 1990, but bikes are a bloody mystery... or should that be misery?

[Donor]

Ok, listen very carefully, I shall say this only wince....go inside and make some cake!

Sure, if you don't want it edible!

[F5 Dave]

hmm, ok for a start if you want to eliminate the PVs just pull a pipe & turn the bike on. The PV will cycle down & then full open for easy kickstarting (closing once started & opening after 4500). so that will show if you've done something queer there.

ok new plugs, the old ones will have got oiled up at some stage & often don't recover. 'chuffing' is symptomatic.

pull the carbs apart & clean out the pilot jets, they could have clogged while off the road.

Further don't expect the head gasket to last, those RZ ones are new-or-screwed as I've found out the hard way trying to reuse them with many different sealants used that have done the biz on other bikes.

if you do look in the pipes & see water that might be a clue, but not likely after such a short time.

Also the full fairing models had a vacuum tap that could leak which will flood the engine, foul plugs. pull off the hose & check,
I can fix those.

[RDjase]

So Daisy the mighty RZ250 has had a birthday, and been given two new pistons.

All went so well, I guess we knew something was bound to go arse rapingly wrong, and no surprise at all, it would appear we have not been disappointed.

She won't start from the kick, will run but very raggedly if she is tow-started. There is a frequent belching (chuffing) from the pipes when she does get close to running, and I think we may be looking at a timing issue.

Now, this poses a question - I have read that the YPVS can be timed, but nowhere can I find how the hell this is checked.

So, anybody out there able to suggest a method for having a check, or even give us some more avenues of investigation to look down?

I haven't explained myself very well here probably, so will sit with lappy on my knee in the gargre with baited breath!

Cheers!

Check you havnt droped the carb balance pipe when you took it apart. Its about 8mm OD, 6mm ID and 80mm long. They can fall down the cases under the carbs

Thats what LC,s run like without it, and it is easy to drop/forget it....................Usaully after having the carbs off and the 3rd call for post classics is being called