Gilera Runner 70 - Recommend me a crank

Hi Guys,

So my 99 Gilera Runner 50 SP has now clocked 15,000 miles, it's on the original bottom end and has had a Stage 6 StreetRace 70cc kit and Malossi gear up kit fitted for the last 1,000 miles or so, its still riding well but on inspection I can feel the slightest play in the crank from the variator side, strangely side to side movement essentially cannot be felt by hand, but up/down/backwards/forwards can just be felt and if I wiggle it around enough I can get a light knock too.

Regardless I think 15k is a decent effort and it seems silly to push it any further and risk damage to the fairly new top end/cases etc.

So what I'm after is your suggestions on a strong, reliable direct replacement crank and bearings suitable for my 70cc set up (I'm perfectly happy with the bikes performance and have no intention of significant further tuning) that will hopefully see another 10-15 thousand miles.

The obvious choice seems to be the Stage 6 HPC - I realise it's probably over specced for my set up but I'm hoping that'll just mean its under stressed. However I've heard good things about BGM also and I'm sure there are others I should consider.. so let me know your thoughts?!

 

Also if I was to do this work myself am I right in thinking the following tools would be needed;

Variator locking tool
Flywheel puller
Oil seal install tool
Crankshaft install tool
Crankshaft/crankcase puller

 

The HPC crank is a good choice, they seem reliable enough.
Maybe invest in an impact gun, so useful for many things, and you can get the electric ones if you don't have a compressor.
You will need a flywheel puller
Fitting the oil seals, I use a suitable sized socket to tap them in.
Crankcase puller is not really necessary, split the cases by gently knocking the end of the crank with the nut put back on so the threads are level with the nut. Use a plastic or copper hammer, not steel.
Bearings can be done, again, by using a suitable sized socket on the outside of the bearing housing. Just make sure you gently tap them so they start off level in the hole, then use the socket to tap them all the way home.
You will probably find they bite on opposite sides of the hole at first. But that's normal.

 

You might want to think about re-painting the engine cases while they are apart, bring them up to brand new looking again.
This is where a dremmel and very small stones come in useful to get into all the little odd places on the outside.
Give it 2 or 3 coats of VHT primer, then a VHT topcoat, and clearcoat for that final shine.
Done quite a few myself.................still got more to do as well..................

 

Thanks for your reply Steve, I've been on to pedparts as well and whilst they said the HPC is good they've also suggested its a little OTT for my needs given I'm not looking to tune much further, and have advised an uprated Jasil crank and SKF bearing set as another option, the cost of the bits is almost half that of the HPC and stage 6 bearings so I'm thinking the Jasil may be the way to go..

http://www.pedparts.co.uk/product/3978/jasil-evo-ng-crankshaft--piaggio-gilera

http://www.pedparts.co.uk/product/149/crank-bearingsseals-c4-uprated-race

Also they've given me a price of £70-90 based on me sending them the engine stripped down but not split to do the work, BUT as it stands they're not taking on anymore workshop work due being busy. So now thinking maybe I am best to do it myself if I can do it as you say without some of the expensive tools, as otherwise it works out cheaper and less hassle to have a shop do it.

I've gone to Jahspeed for a price too as they're local to me and seem to have a good rep, but no response yet..

Guessing I'd need the crank install tool?

 

Not really. I've never used one.
Tap the bearing into a warmed up case from the oven (let the wife go shopping first if you have one)
then tap the crank into the bearing.
9 times out of ten it'll go through without any force.

 

What you could try first, just to get your confidence up a little, is do it with the old crank and bearings first.
Split the cases the way I said, tap the old crank out, remove the bearings, then put it back together again, just so you get to know the feel of it.

 

Good idea Steve, however Jahspeed have since come back to me and I'm going to have them do the bottom end work for me this time around, but will strip/remove/refit the engine myself and refit the top end.

Do you have any re-assembly tips in terms of lubrication? Should I use two stroke oil on the piston/cylinder walls? Am I OK to spin it over on the starter until it catches once it's all back together? I replaced the fuel pipe recently and did have to crank it for a little while until in pulled the fuel through enough to start, is there any risk in doing this with a fresh motor?

Also with a new crank and piston but bedded in barrel, what should I be doing running in wise?

Cheers!

 

Loads of 2 stroke oil on the re-build, add a little to the fuel as well for the running in period.
I normally run it on the stand at tickover for a while, until it gets warm, then turn it off, let it cool down, repeat several times.
No more than 30mph for the first 100 miles or so, then increase to 35mph for 100 miles.
Sounds long but it'll soon pass.
use the starter or kickstart, doesn't matter.

 

OK thanks, I'll be running the oil pump (primed) on the max setting plus already have 1% premix in the tank, I'll probably bring this up to 2% for the first tank then.

 

common used crank is 'rito'' in our shop. cheap price and for a 70cc not tuned cilinder good enough.