new style(92) pivot bushings in older(87) case

[cr750]

Im putting an 87 500 engine together to go in my 92 chassis and i know most people have the swingarm pivot bushing machined out to fit the larger bolt, but im thinking about boring the case and pressing the larger bushings in. Is there something i dont know? or will this work? the aluminium is gonna be much easier for me to drill.

Also, its a .02 over 87, stock porting and head, will it be a little quicker than the scalloped 92 engine? and would you suggest using the later thin head gasket?

Thanks

[CR500R7]

I'm sure Danny drilled the cases on his 86 engined Gen1 AF useing a 13/16 th drill bit.
Check with him and get the low down on it.
Yes, this will work if done properly and then use the larger bushes.

[Roostius_Maximus]

you need to use a boring head, not a drill bit so you can get the proper pressfit, i've done them like that a few times

As long as the engine is tuned as good as it can be it'll be as fast, possibly faster, but theres no reason to look for something else.

you'll probably have too much compression with the thin gasket on that head, i'd cut the head, but i'd ride it first and see if it needs more compression, doubt it.

first thing to check is that the low style pipe you have clears the reed block area, a fatty wont, but a pc or gnarly should

[nmdesertrider]

No problems here with a regular drill bit

[JR650]

i just drilled mine too. i was damn careful about it, but it worked.

[Nodge]

I used a drill bit on one engine, and it worked fine.
I used the same bit on another engine and it cracked the case half when I was gently tapping in the "bushing"

[asteroid500]

ive done 2 engines with a bore hole drill in the mill

[cr750]

Drilled it and it pressed right in with no cracks, guess I got lucky this time

So, should I go with the 92 head on it then? anyone know the approximate difference in volume?

, didnt think about the reed cage flange being longer. 8mm (or .3149 inches) difference according to the parts comparison link, not very much. I dont think it will be an issue, but you say it will hit on a fatty? I trust you, ill have to take a look when I get her in. You think ill have much trouble with the carb getting in there, I figure the boot will flex .315 inches.

[britincali]

You need a newer style intake manifold, not only are the older ones shorter but the angle will make the airbox boot interfere with the shock.

[cr750]

Ill be using the newer reed cage, air boot, air box etc. The 92 chewed the piston, spit some out the bottom ruining the cases. I have this mostly complete 87 engine, cylinder was just bored 20 over with new piston. never put the 87 back together because the covers are the usual rotten magn so I will be using the newer covers and newer clutch, and I swapped to the larger bearing in case for the newer trans shaft. Im going to try and use the 87 4th and 5th gears as well. many thanks

[Roostius_Maximus]

cr750, email me, got some questions about those cases, and can give you some help swapping in those gears

[cr750]

got it back up and running , I used the thinner late model head gasket so combined with the scallop-less cylinder and the 87 style head it is a hard kick. It is considerably harder hitting than the 92 motor that was in it, prolly due to the fact the other was worn out, or the porting on the 87 is better, either way you can tell a pretty big difference.

The fatty pipe went on with no issues what-so-ever, like I figured, why do some folks have problems with it?

my camera is fucked so it will be a while before I can post some pictures of the thing

[Roostius_Maximus]

my fatty was new with papers stil, hit so hard i changed jugs

[cr750]

this one is probly as old as 92', lol, or whenever they changed the name from fat boy, finish isnt that great any more but no holes or dents so ill let it ride, i kinda like that extra hit on the low end, it is Real close at the reed block but it dosnt hit

[cr750]

the 4th and 5th gear helped out my topend pretty well also, guess i can put the stock sprockets back on it, im probly seeing triple digits with 5th toped out, got some good ole watery eyes on it earlier

[dannygraves]

I personally like 14/49 gearing on a stock w/r gear set. still relatively low in the tight stuff and you can still do like 80mph on the fire roads

[cr750]

I have a 14,13, front and 48, 53 rear to play with, it currently has, get this, 16-40 , guy I bought it from had it geared to supermoto or somthing. Ill start by trying 14-48, since you suggested 14-49, I rarely need to go over 75-80 anyway, but it was fun to buzz up the road a couple times though

[dannygraves]

wow, that some serious gearing!
I ran 14/48 on my dunes bike, that should be a good starting point.

[cr750]

yea, when he told me a 16 front i didnt believe it, but when i got a look at it it is big and i counted all 16, it dosnt have any markings so i figured it to be custom or somthing, thanks for the advice on the gearing danny