cleaning up a new motor worth it?

breno

breno

New Member
Hi all,

So ive bought a 2011 grubee motor but the spark plug is facing the wrong way.

My question is since I'm going to turn the head so the plug is facing the normal way is it worth lapping the head and jug as im sure they wont be flat?

While im a it.. is it worth polishing up the combustion chamber in the head and cleaning up any burrs in the ports and flush out the bottom end?

I dont know cant help but think to leave well enough alone..

what are your thoughts?
 
I would say yes, yes and YES! LOL
Since you have to flip the head anyways you might as will inspect and clean up what you can. Some people will tell you not to mess with a new motor cause once you open the head you need to re-torque and some people may not have the tools for that or whatever. I don't follow this logic since every kit I have purchased has told me to CHECK THE HEAD TORQUE before you run the motor. So, if you have to check the torque you are re-torquing the head anyways, doesn't much matter how loose or tight the head bolts were at this point. Pay special attention to the inside of the intake tube if you have the cut and welded style, clean out the metal burs and such from inside so they don't break loose over time and take out your top end...
BTW, what carb did you get with the kit? Is it the new CNS with the clamp on K&N style air filter? (this would be the newer batch of kits)
 
I see your point with having to re torque anyway. Kinda hope I do find some nasties lol make it more worth my while.
I bought just the motor alone and it came with the dodgy cut n weld bend intake. I made my own intake up a whole ago as short and open as possible already matched so that'll save me some time:)
The only pita is I know the bottom gasket will b destroyed when I pull the jug off. Guess I'll have to make a gasket outta somethin.
Reckon reusing the head gasket will b fine if she's nice n flat?
 
It'll be worth the effort even if everything is pristine(lol), then you'll know for sure. Don't forget to check the tops of your transfer ports, casting 'leakage' likes to hide there.

Since its new, if you're careful pulling the jug, you should be able to re-use the gasket. Like, if you're pulling up, but one corner is sticking to the jug use an exacto to free it.

May as well trim your piston skirt while you're in there too, eh? If you pack rags/duct tape over the bottom end, filings shouldn't be a worry.

Oh, after lapping my head/jug 300-1500 I don't even run a head gasket, was a nice power boost, but it'll be harder on my needle bearings. But yea, you'll be able to reuse your gasket :)

gl.
 
Good advice here ^^ And while your at it, you really should replace all those crappy acorn nuts. As they are bad about bottoming out and stripping your threads! Good luck with your build!!

Peace, James
.bld.
 
thanx guys. made it an easy decision (almost seems no brainer now) to go ahead and clean up the new motor. That link in the post above is good too.. straight to the point and easy to read.
Should have asked this before but is using a car polish the best way to bring the combustion chamber to a nice smooth finish?
 
breno said:
thanx guys. made it an easy decision (almost seems no brainer now) to go ahead and clean up the new motor. That link in the post above is good too.. straight to the point and easy to read.
Should have asked this before but is using a car polish the best way to bring the combustion chamber to a nice smooth finish?
Click to expand...

You can but, I described in my doc the way I found it faster, easier and cleaner. Car polish will take some time, but rubbing compound would be better then polish. Also valve laping compound (we used it on VW cylinders), will work.
 
I'm a genuine cheapskate tightwad and still see the wisdom in taking a brand spanking new chinagirl apart for inspection !

that way, YOU can be the QC, and when probs develop, you will have a handle on why they are occurring and repair them quickly.

I am also a believer in applying one of the anti-seize compounds to any threads, especially in aluminum.

Best
rc
 
rustycase said:
I'm a genuine cheapskate tightwad and still see the wisdom in taking a brand spanking new chinagirl apart for inspection !

that way, YOU can be the QC, and when probs develop, you will have a handle on why they are occurring and repair them quickly.

I am also a believer in applying one of the anti-seize compounds to any threads, especially in aluminum.

Best
rc
Click to expand...

Actually being a tightwad (as called by my wife), I prefer the term frugal. I feel that the only hardware installed in aluminum that anti seize should be used on is "bolts" not studs (unless they need to be removed such as stud removal in a car where the manifolds won't pull up over the studs). I locktite (red) to all my studs on these HT's. I also have the tools to remove such studs (heat) should I need to. I also use lock nuts on ALL studs. And on the head..just flat washers, No lock washers. Have never had any stud issue since using locktite, Warning...as I have tried to remove a cylinder stud (on a experimental case) without using heat is next to impossible without messing something up. Just food for thought.
 
Well after opening her up I see the combustion area on the head is already glazed with something making it nice and smooth so I left it be.
Still lapped the head and jug though as the head wasnt flat to begin with. .

I was suprised how much the piston covered the intake port at TDC glad I fixed that up and the gasket for the bottom end of the jug was covering up the transfer ports a fair wack too.
Also found what looked like bits of alloy specks with spray paint over them in the exhaust and intake port glad to have gotten rid of those too.

Also found where the the intake pipe meets the port was ruff as guts too wasnt likely to get a nice seal from the pipe to the head so I milled it nice and flat.

Found a a 1.5mm casting edge on the side wall of the exhaust port right where the port meets the barrel so I just removed it so it looks like the other side of the port

Replaced the top needle bearing with an aftermarket 1 with a stronger cage and bigger rollers.

Flushed out the motor with some petrol and carby cleaner then blew the crap out of it.

Went to use my shorty intake that I made up for an older build but the studs on the new donk are too far apart.DOHH!
Got carried away modifying the intake pipe and ended up stuffing it up so that was thrown across the welding bay somewhere and its staying there.haha

All in all like youse have said def. will be doing this to every new motor I get. Didnt realise how tight these motors are to turn over when they arent ran in either Jeeez!

Think I'll run this one in on semi-synthetic at 25:1.

Thanks for the encouragement and advice guys :)
 

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Made up that new intake tonight..
Had to use the header pipe off a stock exhaust to have the pipe big enough to join to the flange I made up as the standard intake pipes are too small to make a match to the flange port window size.
Ended up just cutting the standard pipe at the weld bend and just welded that on so the carb had something to slide onto. Only annoying part was the clutch cable keeper beneath was too high so I had to cut that down to lower it.
All in all its probly about 40mm in total length but atleast its port matched properly and tappered as far as possible heaps better than the standard 1 IMO.
 

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Well had the bike running gr8 today considering it was running in. I was very happy with the performance. Only to find when I'm on the way back after a 20min ride the clutch is scraping on the cover harshly. Took the clutch cover off to find the whole clutch shaft had moved over to the clutch side and it was jammed there. Spent a couple of hrs trying to move the thing with different approaches and still would not budge. Now I've damaged the sprocket side bearing. Not happy. Will be calling the fella that I bought it from tomorrow and telling him I want a replacement.
Sux that you go to so much trouble to make it run well only to have some other part stuff up I swear I should have stripped the whole motor apart from the beginning now such a shame.
 
Gosh! I'm sry to hear there is some damage in there to the drive shaft parts.

Have a look at Lord Vader's repair section before you make any big decisions.
Hopefully u can get needed parts quickly, and cheaply there in Oz.

Best
rc
 
breno said:
Well had the bike running gr8 today considering it was running in. I was very happy with the performance. Only to find when I'm on the way back after a 20min ride the clutch is scraping on the cover harshly. Took the clutch cover off to find the whole clutch shaft had moved over to the clutch side and it was jammed there. Spent a couple of hrs trying to move the thing with different approaches and still would not budge. Now I've damaged the sprocket side bearing. Not happy. Will be calling the fella that I bought it from tomorrow and telling him I want a replacement.
Sux that you go to so much trouble to make it run well only to have some other part stuff up I swear I should have stripped the whole motor apart from the beginning now such a shame.
Click to expand...

If the clutch moved over into the gear side and is rubbing on the gear cover then the nut on your chain drive sprocket came loose. Tightening that nut inside your sprocket should pull the clutch back where it belongs. They give you the spark plug tool that also fits this nut, I recommend you go get yourself a real socket to fit that nut and crank it on with some good force, you should feel the clutch shaft pull back into its home position as you tighten.
 
Well its all fixed now kinda.. just gotta refit the motor.
I ended up using a hyd. press to get the sucker out, man it was in there tight!!

Only thing was coz I was in a rush I accidentally broke off the back part of the drive sproket housing and had to use some angle alloy to keep bolted it in pos.

After fixing that stoopid stuff up I carried on refitting everything with some good bearing grease and tightened up both nuts F.T with locktite. It looks a little frankenstein now but I'm just happy its all back together and ready to go.
 

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