Heads, jugs and throttle bodies....
Thread Starter
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Seasoned HDF Member
Joined: Apr 2014
Posts: 5,815
Likes: 2,555
From: UK
Heads, jugs and throttle bodies....
So, just a little bit of thinking about where next to go with my bike....I want to do a bit of planning for the winter. Bike is a '14 FXDF 103"
Last winter I did a cam swap to Andrews 57H, and had the heads properly ported and valved. The bike runs great and has already done several thousand miles in this new configuration. I love it..... It's running 10:1 compression with a 0.030" head gasket. Goes like the clappers!
When I had the heads done, they were flow benched with and without the throttle body and I now know for a fact that the heads will flow more air than the current (stock) throttle body can supply.
So there's definitely a new throttle body on the cards to fix that bottleneck. I am thinking an HPI 55mm unit with 1.73" manifold. I will pull the heads again, send them to my porter and have him match the intake runners properly.
But what I am now thinking is while the heads are off, why not get a set of the new drop in HD 110" jugs and pistons at the same time.
I guess my main question is will these parts be a good match? The heads were machined to 86cc and have 1.94" intake valves and 1.61" exhausts - are they likely to work well with the HD 110 jugs and pistons kit? Also, will the 55mm TB be large enough at 110" - I don't want to oversize the TB if I can help it.
Anyway - all thoughts and advice welcome. It just seems to me that while the heads are off again, it might be good to grab the extra inches and bump the bike up to 110".
In an ideal world, I'd like to split the cases, have the cranked trued, balanced and welded, then bore the cases and go to 117" or something. But that's not likely to happen due to the cost and lack of local shops.
Last winter I did a cam swap to Andrews 57H, and had the heads properly ported and valved. The bike runs great and has already done several thousand miles in this new configuration. I love it..... It's running 10:1 compression with a 0.030" head gasket. Goes like the clappers!
When I had the heads done, they were flow benched with and without the throttle body and I now know for a fact that the heads will flow more air than the current (stock) throttle body can supply.
So there's definitely a new throttle body on the cards to fix that bottleneck. I am thinking an HPI 55mm unit with 1.73" manifold. I will pull the heads again, send them to my porter and have him match the intake runners properly.
But what I am now thinking is while the heads are off, why not get a set of the new drop in HD 110" jugs and pistons at the same time.
I guess my main question is will these parts be a good match? The heads were machined to 86cc and have 1.94" intake valves and 1.61" exhausts - are they likely to work well with the HD 110 jugs and pistons kit? Also, will the 55mm TB be large enough at 110" - I don't want to oversize the TB if I can help it.
Anyway - all thoughts and advice welcome. It just seems to me that while the heads are off again, it might be good to grab the extra inches and bump the bike up to 110".
In an ideal world, I'd like to split the cases, have the cranked trued, balanced and welded, then bore the cases and go to 117" or something. But that's not likely to happen due to the cost and lack of local shops.
Thread Starter
|
Seasoned HDF Member
Joined: Apr 2014
Posts: 5,815
Likes: 2,555
From: UK
No ignorance there Robby - I don't know whether they are or not - but I would like to. Kind of hoping that some of the more experienced builders we have here can advise.....
Outstanding HDF Member
Joined: May 2014
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From: Palm Desert,CA
gotcha, well I'm waiting to here right along with you!
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Road Captain
Joined: May 2015
Posts: 627
Likes: 47
From: Nunda
As far as I know 96, 103, 110 heads will all bolt up.
This does not mean they are efficient with each other. Just means they will work
This does not mean they are efficient with each other. Just means they will work
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Joe Kucinski
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From: poway
Assuming the current CR is about 10 to 1 and you are using flattop pistons. Going to a 4 inch bore with flattops will increase the CR to about 10.5 to 10.6.. It's a little high for a 57 cam.. You'd be better off with a can that has a 44 to 48 degree intake close.. If you porter is worth his salt (sounds like he is), a 1.94 intake valve can use a bigger TB fer sure. IIRC the newer FBC throttle bodies don't flow all that well.
