Im going to start a custom engine build on my 93 fatboy hopefuly with in the next 8 months and have it done before or in april of 2011. Here is the list of the parts that i want to order and do to it. I have two different approaches i can go. A cheaper one and the expensive one. They both give me what im looking for, but i dont know the pro's and con's of the engines that i want to use. can anyone help me out? Also not sure what the gear ratios are on the engines, so i may or may not upgrade to a six speed transmission. And if i go upgrade the trnay, to i have to change the rear sproket to acompany the hp and torque gains?

Cheap build:
rev-tech 124 ci engine (comes with muniki 44 carb and air cleaner)
rivera promo 14mm kevlar belt outer primary
dyna 2000 single fire ignition kit (comes with module)
sampson true dual exhaust
rev-tech 6 speed transmission

Expensive build:
S&S 124 engine with IST ignition and super G carb kit
rivera promo 14mm kevlar belt outer primary
sampson true dual exhaust
baker 6 speed transmission

 

Ambitious build! As an S&S 107 owner I'm biased so will offer no view on your motor. You could ease the pain to your wallet by buying the motor first and using the stock transmission for a while, leave changing it to the following year? You will need a beefed up clutch, which you should add to your list! Also replace the primary chain and crank sprocket at the same time and fit a new set of pulleys and belt. If you change the transmission later they will all fit back on.

 

I intend to do so. The Rivira Promo outer primary kit comes with a clutch. Thanks for the heads up with the crank and sproket.

So, i dont need to swap out from a 5 speed to a 6 speed trany to accompany the new bigger engine? if i leave the 5 speed in, wont it be extremeley rough on the RPM range?

 

If price is of no concern, go with the S&S powerplant! You can always change your final drive ratio as an alternative to going with a six-speed and that is going back to the funds available...

Looks like you are on the right path for some serious fun!!! Modding your ride is where it's at!

 

With the extra performance and torque a 124 is going to give you, a three speed will probably be good enough! Joking aside, I have a 107 with much more performance than my original motor and use the same transmission and gearing. That way I get the best out of the bigger motor and I have no wish to fit a 6-speed. My current project is a 6 gallon tank!

I know there are very different opinions out there on these things, but if you change the minimum with your first build using the stock tranny you save some money. If you don't like what you have or change your mind later on it will be easier to afford further improvements. I have owned my Glide for 20 years now and it is a project in continuous development! That way I avoid truly big payouts for stuff.

And an S&S 124 is a big enough bill to pay....

 

I like the "Made in USA" Ultima engines, and think an Ultima engine would be a better choice than the Rev-Tech. One low price, about $3499 for 100-120" engine at jirehcycles. I have a 113" in our bagger and use the Energy One extra clutch plate kit ( about $106 ) and heavier spring and it has worked well for about 12,000 miles with our setup - about 114 lbs foot torque. Unless you intend to run more than 120 mph, the 5 speed should be OK - I know our bagger will haul our 500+ pounds up to the 120 mph mark, but the bike is not as stable as I would like at those speeds. I think you can change the gearing with the sprocket for a little more top end, 1 tooth makes a difference and you can continue to use the same drive belt. overall, maybe $4000 total ( engine, clutch pack , gaskets etc.) for a pretty good running fatboy.

The recommended 6 gallon gas tank sounds great....

 

+1 on the Ultima's Rev-Tech have been around for a while and still have some of the original problems plauging them. Better clutch and 5 speed are ok unless you plan on doing a lot of distance riding then the 6 speed is nice. 0311, must be a former Marine!!! Hope this helps.

 

If you don't have one I strongly recommend a True-Track Trackula kit. Makes a remarkable improvement to stability, especially when fully loaded.

My wife and I travelled 2,500 miles from the UK to Poland and back this May with our 5-speed and stock gearing. The benefit of using a bigger motor is to get improved performance. Does not make sense to me to load it up with more gearing, such as a 6-speed, to cancel out the increase in torque!

But I have gone on about that a lot here on HDF!

I'm working on it, although I do plan to take my time.

 

well if that is the case, then i will stay with the stock 5 speed. if i dont have to spend the money on something im not. thanks to all for your help

 

yes it is. $9k latter but well worth it in the end....