PDA

View Full Version : Finishing thoughts 883/1200


Wannabee
8th June 2005, 06:52
Hello!

Finally my brand new 883 is approaching Finland's coast :clap and now is time to start planning the 883/1200 conversion for real. I have already decided to go with the original cylinders, bore them and put Wiseco's 10:1s in. Heads stay stock. Still I have couple of things, I hope you could help me with, so I would be better prepared to move on.

1. ignition
2. squish height

As far as #1 goes I already know (thank's to you), that the spark is triggered from the flywheel and cannot be adjusted.

What I don't know, has the 1200 models ignition module different advance curve and if so, is it better for conversion than 883's curve, or is the 1200 models curve similar to 883 only the spark being triggered from a different place?

Twin Tec sells a TC88A module, which has many possible curves and it fits 04- Sportsters but the price is over 400, so I thought maybe a simple switch to 1200's module (if possible) could save me some money.

And here goes #2:

Buzz Buzzelli says in his "Sportster performance handbook", that the cold piston-to-head clearance should be set very close (0.020 to 0.025 inch), because when engine warms up the clearance grows about 0.040 inch and the squish stops being effective when clearance grows over 0.065 inch.

When warming up, is the growth of the clearance same with the original and forged (Wiseco) pistons?

How big squish heights have you used and what kind of experiences have you had with them?

I understand the benefits of the tight squish and want to use it as much as possible, but how unpractical will the bike then be? Will the pistons bump the heads if I "accidentaly" rev the engine even just a bit when I start it up?
Does the engine need to be warmed up exceptionally long time before I can hit the freeway?

Ok I think (and probably you too :p ) that's enough for now.
Again, any suggestions, hints etc. would be greatly appreciated.

garman68hd
8th June 2005, 13:11
I have already decided to go with the original cylinders, bore them and put Wiseco's 10:1s in.


I'm no expert, but I'm sure I heard that the cylinders on the rubbermounts are not particurlarly good for boring, and that new cylinders are recommended when upgrading.

Anyone have any info on that?

Oh, and welcome to the forum :)

pquirk
8th June 2005, 13:50
I'm no expert, but I'm sure I heard that the cylinders on the rubbermounts are not particurlarly good for boring, and that new cylinders are recommended when upgrading.

Anyone have any info on that?

Oh, and welcome to the forum :)
I think someone fed you misinformation. Boring the cyclinders is actually the method of choice since they're already seasoned and can then be matched to the pistons after boring. And it's way cheaper. Just make sure torque plates are used. There's a ton of info on this in the conversions section, check it out.

As far as the ignition question goes, I'll let someone else chime in on that who has more expertise.

Turbota
8th June 2005, 17:09
I use the SE ignition module on my bike. It has the same ignition curve as the stock module, but does 2 things different:

1. Increases the rev limiter to 7,000 revs. This is good for me since my motor makes it's max power up to 6,800 revs. The stock module had a limiter of about 5,800 and I would not get the benifits of all my engine mods without the higher rev limit.

2. Although the timing curve is the same as stock, this module [decreases] timing 5 degrees at Wide Open Throttle (WOT) only. This is good for me since I have 10.5 -1 compression, so it has prevented detonation at WOT. Again, other than WOT, the timing is the same as stock.

If you keep the compression on your motor to 10.0 -1 and don't go with too big of a cam, I think you would be better off just keeping your stock ignition module. Believe it or not, more than one very good engine builder has told me that the stock modules in these bikes have a [very good] spark curve as they are. Replacing the module with some kind of an adjustable spark curve module may not get you any more power unless your motor is highly modified.

Big_Baazzoo
9th June 2005, 07:55
I used my stock cylinders and the same wiseco 10-1 pistons with a Crane module. no pinging rev limiter set at 7000rpms. She makes power. I don't know how much FASTER i go, but I sure get there quick.

stevo
9th June 2005, 08:06
DO NOT go less than 0.030" squish/quench height on a street bike...

You can sneak a touch lower on a race bike that is pulled down regularly....but on a street bike you need to allow for some carbon build up over time...


Becarefull what you read in Mr Buzzelli's book...he's an author ..NOT an engine builder


If you're going to change the ignition module then go for a programmable Crane unit.....

this is actually the FIRST thing I would do on a new sporty, same as on Twinkies, without the ability to fine tune an ignition, you need to leave a bigger safety margin in your build

Wannabee
10th June 2005, 11:31
Thank you guys! :xlrocks ,and you make it rock!