Dan Hodges Bang for your Buck Engine Mods

[Jaymo]

I haven't been around here for a while. Work has been so busy that I haven't had time for messing with the bike for a while.
I'm still having trouble with the Keihin CVK36 carbs and have been looking into other options, such as Mikuni RS36 and some Individual Keihin non CV copies.
I stumbled upon this thread and read the entire thing.
Pure tech gold. 1%, 2%, 3%, and 5% gains don't sound like much until you think about how they add up to sizeable gains.
Plus the fact that any gain is better than a loss.
This has been very eye opening. I've never felt comfortable with doing a full port and polish of cylinder heads.
Port matching, removing casting flash, and roughing up the intake port inlet and polishing the exhaust port outlet?
Yeah, I can do that without ruining the head. I know that less is often more, and doing a little work for a little gain is a lot better than doing too much and ruining the flow or killing my compression.
 
Since I'm not trying to build a race bike out of my 81 Venturer, I can live with smaller gains and less than absolute max possible top end HP.

Re: Ignitech ignition. I've heard great things. Tough call. Keep working at the Keihins, install Ignitech and use the TPS on the Keihins?  Replace the Keihins with RS36 Mikunis? Dunno.

[BrettS]

Don’t go there! That’s not even my biggest regret.

[makzy]

Well ,,,, I have to say, with a lump in my throut, I wish I still had mine, ancient history now.

[BrettS]

Your at least one up on me Makzy, I never finished my FX

[makzy]

Sounds awesome Bryan but I don’t have a laptop ? I’ll have to make do with flat sides

Get on it Makzy sounds like fun finding out.

No mater what two bikes we were on Jonesy I reckon you would still be waiting for me at the end of the twisties. ?

Ha Ha Ha, yeah probably, if I was 30 years younger maby not! But I don’t really care, I do really like all the technical details of all sorts of things, that’s just who I am, and, I’ve done some really good things in my time, an FJ that could do 125 mph just one, but it’s great to see all you guys playing around and doin ya stuff so keep up the good work and keep postin it so I can learn some new shit! Because that’s what I like about you mob. Cheers.

[BrettS]

That’s crazy good, all for $1000 
Maybe by the time ya mates work that out my next building loan matures.

[AussiXS11G]

Bretto - 17km/litre and 114hp at the wheel - 

on a side issue -
BTW - my mates with the Laverda race bikes (with flat slides) are trying to work out a way to retrofit the TPS to their machines.....

gratuitous bike porn.....

[BrettS]

Get on it Makzy sounds like fun finding out.

No mater what two bikes we were on Jonesy I reckon you would still be waiting for me at the end of the twisties. ?

[BrettS]

Sounds awesome Bryan but I don’t have a laptop ? I’ll have to make do with flat sides

[AussiXS11G]

TPS - throttle position sensor

the BS36 carbs come with TPS (standard on the XJR1200/1300) but you need the Ignitech box (or similar) to connect the TPS which will adjust the ignition timing relative to % of throttle opening compared to engine revs.

If you only make one modification to your machine - this should be it - well two really, carbs and ignition - using the OEM ignition trigger, you should be able to get out of it for less than a $grand I reckon

Oh... and what Jones said, Bretto

have a look in here....
https://www.dropbox.com/sh/jswk7cuz8d7oste/AACpNt7xHL6sYR2QfCEqRhVea?dl=0

[makzy]

Yeah I understand a lot of what he’s saying, played with speedway engines years ago,
I didn’t polish the inlet ports, just tidied them up a bit and matched the carb mounts, left them rough and swirled according to info I had back then. Cleaned and polished the exhaust ports and matched them to the pipes, mind you, I’ve never run this head so who knows if it is an improvement or a failure?

[Jonesy :-)]

My stock standard 1/2 worn out unit still goes fast enough to scare me, see you on the twisties when you get it all hotted up Brett. Just slow down and wait for me on the straights. 

[BrettS]

Hey Brian, I gather TPS is your new throttle system?
You raise a great point, the big bore kit would easily go the $1000 after machining I think.
I got lucky and it only cost me $200, might just need a new gasket fingers crossed.
I may have skewed the advice listed of to the side at the moment as I’m concocting the plan of the block to head. I do believe displacement and compression gains are the foundation of any good plan.

Hey Makzy, if I can understand most of it it can’t be that technical. I didn’t even really understand dialing a cam in a few months ago but am starting to understand.
There are a few easy things here but I still need to clarify what he is saying for sure as to cams.
Seems the best option is the late US head ( large valves, ports and bowls) but the pistons of early US and Oceania are not domed on top and this will cause a drop in compression. You need to either use the late US domed pistons as well or the wiseco kit. Taking some of the head as well to up the compression.
Interestingly he explains why we armatures should not attempt any metal manipulation upsetting the flow. Only thing he suggests is to modify manifold to suit head. But I need to understand that better.
I also need to understand what he suggests about the cams. Seems the early ( our) cams are included in the “hot set up” but he also states the shorter duration late cam will increase compression by closing the intake valve early and this can increase power in a different range of revs.
I’m More into low end grunt than top speed, I like feeling the g’s coming out of a corner and going up a hill. Passing power is great but even if I went to the track I don’t think I would often go over 160kmh.

Oh I wanted to remind you, polishing inlet ports is old school now they rough them up.

[AussiXS11G]

hey, don't do as I do, do as I say......
I dropped a bomb on mine - polished/balanced/lightened crank and rods, head work, rebore, bespoke exhaust, it doesn't stop there....

but bang for buck - just need to make it more efficient

[makzy]

Very true, but it’s still really interesting to know what the real tech heads have to say!
I revel in it, but would I be bothered to go down that track thouroughly? Probably not! Your plan is simpler, easier, and possibly come up with similar results.
Some people are folders, some people are scrunchers! But still the job gets done.
Again, I thought it was really interesting.