Resin & Crank cases - and different Cylinders. How to re-align?

Right
so you've cut your engine for a Pro Race (or whatever) and you want to change cylinders but nothing lines up. What do you do ?
Well I have a motor cut for pro race and I'm rather taken with the MHR Team 2 at the moment. I slapped it on there (I'll spare you the details) and I liked it ! But it was obvious that some heavy aligning was going to have to take place. So here goes.

You could use a flat plate for this - it doesn't matter. I just happened to have a plate cut from 5 mm alloy for the MHR Team 2 so I used that.
Step one is to make sure it's flat by surfacing it on some glass plate with emery paper bonded to it. Then wash it and stick a nice sticker onto it. This one is a Maxiscoot sticker. They would be proud....
https://www.flickr.com/photos/116877957@N08/13903561394/

Then you spay it with some silicone spray, or some plastic restorer (it's the same thing) and give it a good wipe with a tissue.

Then you bolt it onto the engine:
https://www.flickr.com/photos/116877957@N08/13903196883/
You can see the problem right there. It's the massive overhang on the left. The case is cut back farther for the pro race 'about as far as it's sensible to go in fact). The Team 2 is waaay out - so we need to fill that. There are lots of other things that need doing as well, but for the moment we are concerned with the alignment.

I prepared the surfaces by scratching them up with a carbide bit and then washing them with detergent then acetone to de-grease (just to be sure):
https://www.flickr.com/photos/116877957@N08/13903191703/

Then you apply resin. In this case it's Quicksteel - perfect for this application. In tricker bits I use JB Weld. It takes 24 hours to go off but it NEVER comes un-stuck and it's tougher than coffin nails. Quiksteel is just fine for filling non-air tight bits where the case is doing the backing up.
https://www.flickr.com/photos/116877957@N08/13903526044/
https://www.flickr.com/photos/116877957@N08/13903176633/
You can also see that the guy that sold me the MHR with the plate hammered one side. So I used it this way up and surfaced the better side (which is in contact with the block). Lazy. But if I'm going to fit a crank with a longer conn rod, I'll get a new plate, thanks -
In fact this motor block is second hand and was obviously hammered too. None of the scratches and dings around the crank area are me. Only the flowed cases and where it's been enlarged for the MHR. And the filthy finish around the transfer area where I did it 'rough and readty' to try the MHR. This is why we are here. Going to get it sorted.
I digress.

Then you just dremel gently away any overlap which might be holding your plate on (if I had used a big stickered plate I could skip this bit)
https://www.flickr.com/photos/116877957@N08/13903162863/

Undo the bolts and take off your plate:
https://www.flickr.com/photos/116877957@N08/13903517234/
You can see that the 'pro race' profile is starting to dissapear. To get things right, we need to dremel a gasket on the MHR, fit it onto the engine and see where the discrepancies are. Then cut the engine and the gasket correctly, put the gasket back on the cylinder and correct the base of the cylinder so everything aligns. More of this later. We have some sculpting / finishing to do first. Not to mention filling the other side. To say nothing of the rear transfer (which is massive on the MHR)....

And it's flat ! No need for complicated machinery to mill it flat.
https://www.flickr.com/photos/116877957@N08/13903513424/
In fact it's ever so slightly recessed - just enough for when the sealant does it's thing. Obviously, when you apply the sealant- you concentrate on the flat metal. The excess splurges out a bit onto the resin and a smooth transfer is assured. This is all about gas flow. No kinks. No weird jut-outs or bends.

If you were dealing with a basket case - you could fit a flat plate and then fill the entire transfer with liquid JB Weld and start from scratch with the dremel. In the case of a partially wrecked cylinder deck, a flat steel plate with a light coat of silicone would probably work with JB Weld leaving a perfectly true surface. Food for thought.

It looks a mess ! However, we shall see to that later and get a nice smooth contour & finish like the rest. This is just stage one. Get this bit right and the rest is just dremel, sandpaper and a few other nick-naks.....
Lots of work to do - but I like this part of engine prep.
Hope this gives somebody some ideas -
More to follow -

Part Two - the dark side......


So here we are again. This time starting with the admission: There were a few things I wanted to get sorted here and now is as good a time as any -
https://www.flickr.com/photos/116877957@N08/13906116603/
This bit is more important in my scoot because the reed box is raised. Why? Picture coming ! I have a reed box and an open engine to show you ! It's not rocket science. When you see it, anyone that understands what the rear transfer is for will get it straight away. Got an aerox/Mach G ovetto/Neos and want 2 free horsepower ?

So filling in this bit helps because it's close to the mouth of the reeds. If you think a carburettor is like a dick and the petrol is the sperm, we want a nice vagina right here. . That is, if you want your cylinder to get pregnant.....

https://www.flickr.com/photos/116877957@N08/13906056875/
A look from the outside. Again, flat alu, tape and silicone spray. Clamped down, and with judicious use of the quiksteel, there will be the minimum of surfacing. But there will be some. More of which later. Don't ask me what the lemons are doing there.

Here we are un-clamped. Lots of overrun but not much on the actual metal join part. And that's what counts boys and girls. It will still require surfacing, but the less you mess with that, the better. Unless you have a very big, very expensive machine. And you want to put a Bidalot C48 crank in there......
https://www.flickr.com/photos/116877957@N08/13906053895/

Same technique as before for the transfers on the other side.
https://www.flickr.com/photos/116877957@N08/13906456994/

Looking good from the top:
https://www.flickr.com/photos/116877957@N08/13906447064/

Looking good from the side.
https://www.flickr.com/photos/116877957@N08/13906083353/

Now this big ski jump thing here- this is not something to imitate when you're actually shaping. It looks great - but really I'm just dolloping resin on here with my finger and a curve gets me in the mood. It's the transfers I'm interested in. The join between the cylinder and the case. In any case - the skirt of the cylinder won't go on with that there. But it's better to put more on and take a lot off than put too little on and find you've not got enough on there to get both sides even.
More to the point, the gasses going up the transfers to the cylinder are not coming exclusively from the reed box. So be prepared for a shock the next time you see this bit.

The name of the game at this point (when you get the dremel out) is symetry. It's not as important as in the actual ports of the cylinder - but every little bit helps. There will be a fair amount of putting the cases together/taking them apart and a whole lot of dremmelling to get it right. More of which later -

So next we let all that go off and then have some fun sculpting this weekend. Time allowing.

Can't wait to try the MHR on there when all this is done. It is going to be seriously violent !

More soon -

 

Here we are with part three.
After quite some dremmelling and a deal of faffing about...

The ignition side after a little dremmelling and quite a bit of finger sanding.
https://www.flickr.com/photos/116877957@N08/13893126001/
Everything's got more rounded and steeper - and the two-step metrakit profile has gone.

Here is the case from the side. Still fugly, but we will deal with that. But that's quite a run into the transfers.....
https://www.flickr.com/photos/116877957@N08/13916671484/

Here are the transfers with the cylinder on. Looking pretty good ! But there's a bir more work to do to get a nice seamless join.
https://www.flickr.com/photos/116877957@N08/13893130646/

Another look -
https://www.flickr.com/photos/116877957@N08/13893123932/

This side is not too bad either.
https://www.flickr.com/photos/116877957@N08/13893121922/
But you can see we have lots to do with the rear transfer. This cylinder is a swiss cheese. Look at the entry for the rear transfer FFS.
What a monster.

Other side is dremelled the same but not finger sanded yet - and I haven't looked at the alignment. So lots of work to do yet. Looking at these photos, I'd like to do one or two things to the base of the cylinder too......

Keep you posted (if anybody is interested).

For the un-initiated- it looks like this stock..... https://www.google.com/search?q=carter nitro&client=browser-ubuntu&hs=soc&sa=G&channel=fe&hl=fr&tbm=isch&tbo=u&source=univ&ei=amRQU_6ROYSROJ--gbgG&ved=0CCgQsAQ&biw=1624&bih=912#facrc=_&imgdii=_&imgrc=4o3BNmGvhJ_HiM%3A;0ItcXR-QsE8iCM;http%3A%2F%2Fimg252.imageshack.us%2Fimg252%2F5918%2Fdscn0511yj1.jpg;http%3A%2F%2Fforum.mobcustom.com%2Fgeneral-(50-a-boites)%2Fphoto-de-clappets-dans-carters-am6%2F;615;461
The route to the transfers is essentially blocked and everything is pushed into the transfers via the crank housing.

 

Pure inspiration, fantastic work. I have a set of damaged piaggio cases that are gonna be getting a practice workover over the next few days because of this post!!!!

 

Thanks Nathanael. Makes the photos/hassle with flickr worth it !
Did a little tidying this evening - this is the current state of affairs:
https://www.flickr.com/photos/116877957@N08/13905189361/
Photography makes it look much worse than it really is.
The major issues are dealt with. There is some tidying up to do around the new resin at the base of the skirt. There is a hole in the old resin (air bubble that I popped when sanding) that needs a little go with the dremel and filling with JB weld. You can see it on the left case (ignition side) just under the 'wing' - it's tiny - but I can suck air through it - and this will hobble the performance. No problem. Just make the hole bigger and fill with JB Weld.
The rear transfer needs aligning with the massive tranfer of the MHR -
Then I need to surface both halves of the clam, bolt it together and have a look at the symmetry and probably correct a few things.
Then we get out the magic finishing tool and take some photos - that bit's gonna be cool !
More photos as we progress -

 

https://www.flickr.com/photos/116877957@N08/13909740096/
So here is the hole I was on about. You might think that since it goes through to the rod placement and the rod is in there - plus the cylinder over that, and all the bolts, it would be air tight anyway. You'd be wrong !
https://www.flickr.com/photos/116877957@N08/13933296014/
hole made bigger for the JB Weld.
https://www.flickr.com/photos/116877957@N08/13933294054/
This is the stuff. When it's about air-tightness - this is what I use. I've had trouble with quiksteel - but never JB Weld.
https://www.flickr.com/photos/116877957@N08/13909725511/
Just have to wait 6 hours when it starts to go harder and then we can push on it and force it into the hole good and propper. Then we sand it flat & that's the end of the matter.

Now about reed boxes -
This is what you get if you slap a reed box on a minarelli:
https://www.flickr.com/photos/116877957@N08/13933290054/
Things are even worse than they appear here because the reed box can't go all the way in because of the bolts & the filled admission tract in my case. The beak of the reed box is right down near the crank - and the end of the beak is actually past the first transfer entrance (directly above). I think that the stock reed box is longer and more acute - which makes things worse still. This is a VL 14 by Malossi. The best there is.

Now the first transfer (or rear transfer) is angled inside the cylinder so the wash goes up to the roof of the combustion chamber. It pushes the exhaust gasses out of the exhaust port when the cylinder is on the way down. With the beak of the reed box beyond the transfer, the gasses have a harder time getting in there. So this washing out process is less efficient. Not only that, but the beak is pointing down towards the crank - which is great if you run a stock engine - because there is no open path to the transfers anyway. But in this case - there is a bloody open freeway to the transfers.

https://www.flickr.com/photos/116877957@N08/13932898363/
Here we are with an RSE wedge. You can see that the beak is now closer to the transfer, and slightly further back relative to the opening. In this case, the intake gasses have less distance to cover and no 'about turn' to get up that transfer. And the beak is pointing towards that freeway to the transfers.

https://www.flickr.com/photos/116877957@N08/13909729236/
Here we are with an RSE wedge plus a home made 5 mm plate. Now the beak of the reed box is just behind the entrance of the rear transfer. In this case the gasses spew out of the reed box and are very efficiently drawn up the rear transfer.

RSE racing have dyno'd this modification and they claim a 1 to 2 horsepower advantage with the wedge. They are not prone to exaggeration. I believe them. It makes a very perceptible difference. Before I knew about RSE racing my buddy and mechanic mentor put a flat 10 mm plate under my reed box and it made more of a difference to the performance of the scoot than going from a stock carb to a 21mm Del Orto......

It goes without saying that if you use a plate/plates to get the reed box properly set up, they need to be surfaced, and you need to use sealant. Using a vulcanised reed box is also mandatory because the standard item relies on a gasket underneath it and the rubber intake pipe so it's air tight. It's just not good enough for this type of modification. I keep banging on about this but it's no good modifying the engine or kitting it up if it's not air tight. This blocl will be pressure tested before it goes on the scoot. I advise anyone to do the same.

 

I notice you fill one of the bearing lube passages on each side. Have you noticed any extra wear and tear due to this? Or is the one in the transfers good enough to do the job on its own?

 

No - in fact they are not filled. There are two types of Minarelli case. One has the lube holes near the admission and the other has them in the transfers. This case has them in the transfers - so the redundant castings in the admission tract are filled. The lube holes are there in the transfers - and are in fact larger than stock. I re-drilled them larger to help the lube. You can see them in this photo:
https://www.flickr.com/photos/116877957@N08/13906447064/
But the massive entry hole is filled because it fucks up the flow to the transfers. It's just that everything is full of dust at the moment. If you blocked the holes to the bearings with a 70 cc kit decently set up, it would probably run for about 10 minutes.....
My other two cases have the lube holes in the admission. I have photos somewhere. The main thing is that there is one for each bearing and that they be of sufficient diameter to let enough juice in there. I have never had a bearing or a seal fail. Only a roller cage in the little end bearing because of a carburettor blockage (in the slow circuit). Now I'm wise to it, it won't happen again.
Needless to say, when it's ready to go together, everything is scrupulously cleaned and blasted with compressed air.
You'll see when I post more photos -
I'll try and take better photos in the future.

 

Here we are. Finished for today. Time to relax !
https://www.flickr.com/photos/116877957@N08/13948228714/
so the main transfers are done. Just the rear one to finish. It's close.
https://www.flickr.com/photos/116877957@N08/13924672176/
Here's the other side.
https://www.flickr.com/photos/116877957@N08/13947778665/
From the top. Looking more like an MHR !
https://www.flickr.com/photos/116877957@N08/13924670012/
This is where it all comes blasting in. You can see the rear transfer is still work in progress - but this one is easy compared to the other two.

 

well they do look nice.think ive found a UK supplier for a afo5e barrel.would love to have my case done for smooth flow.any ideas on improving the flow and minimizing losses.

 

What kind of scoot is it Jim?

 

vision cases.afose.haven't got the barrel yet,its a malossi sport 70.found an adapter for admission but don't think its for mine but it wont be too hard to cut one similar.

 

I'm sorry Jim. I don't know that case at all. But all the usual suspects apply. Aligning the cylinder to the case is a good start.

 

HairyJim: If you are going premix then plug that hole where the oil pump sits. Fill it up right down to the crank.

If you take the reeds and inlet manifold off and look in you will see a bridge in the opening. This can be given a knife edge and thinned out a little. Some people remove it alltogether. Others say removing it completely weakens the case too much.The roof of that area can be raised also.

From memory the intake tract has a step in it, this can be blended to smooth it.

Its been a long time since I have had a set of those honda cases in my hands so cant remember if there is anything else obvious that can be done with them.

 

You're a dark horse Nathanael!

 

luverly...so no big probs to look out for.would like the bigger oil ways.cant be too careful on a lump being pushed,especially one this old.had an a35 and a few other A series motors years back and read the vizard tuning book..good stuff in there bout carb moding too.not many carb mods get a mention.fly cutting,knife edging,screw profiling,chamfering and enlarging throats.not hard with a dremmel..prefer to be running premix and it tidies the engine up too.found a few cheap bits to finaly finish the chink online...so do that first cos its unreliability is known..slowly get the vision ready and do the lump as a VERY SLOW build.(parts).just gotta not spend too much here..if i had a modern Honda ide have loads of cheap parts from here to rebuild it..do need a couple of clutches though..mmmmm.NATH...is your ape window a one piece or two..both types running round here.had a chat with a driver and he said the shop is the one i thought it was..bout 20klm out of town ...near the Honda dealer....gotta get bits.speedo cables about £3 complete.cable inners 20p.bulbs 30p(head light)forks £10 pair built.but no way of knowing if they suit mine.

 

The window looks like this http://img.photobucket.com/albums/v603/mbclubph/DSC01888.jpg