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RGV250 crank issue.

A routine piston examination turns into something more serious.

Out of curiosity, and perhaps stupidity, we decided to remove one of the cylinder heads to examine the condition of the cylinder and piston. Apparently you can tell a lot about the way the engine is running by the markings etc on the piston crown. Ours looked very good, the piston looked almost new with hardly any markings or deposits on it at all. What we could see of the cylinder also looked very good, with some cross-hatching still visible. So, we were happy. Until that is, we put the head back on and fired her up. It sounded terrible, something was not right, the engine had lost its crisp sharp “zing” sound and instead was sounding very rough. There is an additional vibration as well. Fuck.

We called Thomas at Aitken’s Motorcycles (it was his old bike) and described the issue. “You did use a new head gasket when you put it back together, didn’t you?”.

We didn’t know it was a compression gasket and cannot be re-used. Fuck.

So, we ordered new head gaskets, which were duly fitted, but it sounded the same. Fuck it.

Aitken’s suspected the bottom end, possibly the main crank bearing, it would need stripped to examine the crank which is an engine out job. Ah fuck.

After procrastinating for a few weeks using the excuse that we had other bikes to work on  (yeah whatever!) we eventually started pulling the sick little RGV to bits. Once the bodywork is off and the all the fluids drained, we took off the carbs and disconnected all the hoses. There’s only a few bolts holding the engine in so it comes out quite easily. Being a little 2 stroke it’s also quite light so it’s easy to manoeuvre.

Engine out
Engine out

The next problem was that the flywheel needed to come off, and we didn’t have a puller. Apparently a KTM one will fit and is a fraction of the cost of the Suzuki item but we didn’t know that at the time. Steve however,  knew of a friendly mechanic nearby who said he would remove it for us. After dropping the engine off Steve spoke to the mechanic on the phone to explain that we just wanted the flywheel removed as  we were going to split the engine and examine the crank. I didn’t witness the conversation but from what we got back I assume it went like this:

Steve: We dropped our RGV engine off and were wondering if you could remove the flywheel?

Mechanic: No problem. Anything else?

Steve: Yeah, can you completely dismantle the whole engine, clutch, gearbox the works. And then just dump everything in a box. Don’t separate the fixings or anything like that or take note of what went where, it will make it more interesting for Al to put back together.

Mechanic: Can do. Anything else?

Steve: If it’s at all possible can you bend one of the con-rods and loose a few small but important parts? Maybe the primary drive key?

Mechanic: OK, that will be $100

httpvh://www.youtube.com/watch?v=toEa4ZmKhME&feature=related

 

RGV250 Engine completely stripped
Fuck!
RGV Engine in pieces
Fuck!
RGV Bend rod
RGV Bent Con-Rod

Bit like going to the doctor for a check-up and waking up the hospital with your testicles removed. Note to self – Never let Steve make a doctor’s appointment for me.

We’ve no idea why he thought it would be helpful to dismantle the whole engine and gearbox, especially as the RGV has a cassette gearbox, it comes out as a complete unit and there is no need to take it to bits. He obviously though he’d done us a favour though, so we just took our box of bits and left.

With the crank out, we can see there is some play in the bearings, particularly the centre bearing but I’m not sure how much is too much, so it’s been sent to Graham Selwood at Crankshaft Rebuiling Services in Darwin to examine and probably rebuild.

In the mean time I started to put the gearbox and shifting mechanism together.

Shifting mechanism partially assembled
RGV Shifting mechanism partially assembled

 

Checking the tolerances of the RGV250 shifting forks
Checking the tolerances of the RGV250 shifting forks

The Suzuki manual isn’t that clear so by using the exploded diagrams on CMSNL and asking a few questions of the very helpful folks on the RGV250 Forum it’s now in one piece again. It may even be correct.

Gearbox assembled
Gearbox assembled

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