700fi Motor Build - Unleashed UTV

Ok after a few months of testing I wanted to do a write up on my experience with my recent testing with my new motor that Unleashed UTV put together for me. I wanted to put some hours on it before I said anything.

Since there are not to many built 700fi motors out there I wasn’t sure on what worked and what didn’t. So a lot of testing happened and a TON of hours went into my car trying new things to make this 700fi perform better; we found something that really works!

What we finally came out with was a petty descent power package over the average bolt on exhaust intake combos out there-
It consists of a +5mm stroker crank taking it from a 686cc to a 727cc. 11:1 High compression piston. Stage 3 cam. Dual valve springs and Ti retainers. We left the head and valves alone for now; mainly to see how it did with out modding the valves and flow; this also helps keep cost down quite a bit.

Well after a few hiccups with getting parts from Yamaha(seals) we got the motor all together and running smoothly. I then brought it over to get dynoed by Wellers(big shout out to them for squeezing me in) and got it running even better; we were over 45hp before any fine tuning was done. One thing we notice was we needed to work on the clutching ( this I think was holding us back on making a few more hp) so I took it back to Unleashed and Champ swapped out some weights and gave those a shot for the time being.

First time home with it I put a few hours of easy riding on it breaking it in but the need for speed was coming over me. I then got on an open road in my neighborhood and punched- it flew up to 67mph like it was nothing!!! (Also the rev limiter was set at 8k- unlike other guys that bump the rev to get more mph) It climbed so fast from 50-65 it was nuts! I then let off and went back home- the motor felt like it still had more but was felt like it was limited from the clutching.

The next test was the Glamis Night ride. Greg(owner of Unleashed UTV) and I headed out to do some real testing with my new motor. When we got there we did some little rides and I quickly noticed how much low end punch it had! I thought I might have lost some of it with doing the high rev cam but soonly noticed that the motor is mainly in the highier rmps anyways in the dunes; so it seemed to be fine. I also noticed full throttle was not needed for most of the hills that before needed them before the motor work. I could cruise with ease and not ever have to worry about if I wasn’t going to be able to make it up any of the hills. It made duning a lot more comfortable because I felt at ease with the extra power; knowing that I had it there when I needed it, rather then being maxed out all the time before.

Coming back to camp I did a few high speed runs along the flats and was hitting 67mph again! Before I could only hit about 50 in the sand with my last intake exhaust combo. I am running a 7 paddle smoothie skat trak combo on Douglas rokstars. After this I was very impressed! Next day we did the real test and went to China Wall- one of the biggest hills in Glamis. After watching a few cars not able to make I gave it a shot- and was completely amazed on the speed I was about to keep while going up it. It went right up it with ease-making it the first 700fi rhino that I know of that has made it up China! We continued to ride the rest of the weekend with no issues and never failed to impress me.

Next trip I did to test out the low end power was a rock crawling trip to Box Canyon in Florence. And again thinking that my low end would have suffered from the high rev cam would come in to play never seemed to be an issue. The motor loved to crawl through the boulders and fly up the big hills we I felt I needed to give it some extra gas. All and all I was very impressed on how it did and couldn’t have seen how it could have performed any better.

The motor seemed to run cool and very smoothly. For anyone that has really watched the 700fi motor run; I am sure has noticed that for some reason it has a bad vibration (a lot worse then the 660). But after installing the new crank and piston; it seemed to run better and have alot less vibration. So I am very pleased with the out come and cant wait for the heat to go away and riding season to come back so I can drive it some more!!



*****So if you have a 08-09 700fi and want more power then the average guy that has a pipe and an intake; then Unleashed UTV is the place you need to call. Mike, Champ, and Greg will make it right for you with anything that you will need to make your 700 run better. Also if you have any questions - give them and call and pick their brain-never a question too stupid to ask!
They are a good group of guys that are very knowledgeable on the 700fi also including the Rhino 450, 660, Teryx, Ranger, Rzr.
They can help you out with pricing and building you the perfect power solution/needs for your car.

Unleashed UTV 602-246-4011

This is a great write-up. What other mods do you have in mind?

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mods to come are bored TB, larger injector, port and polish, larger valves.

Sounds like a performer!

Was it dyno'd?

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it does alright- it does alot better racing on flat ground then up hill- I will get the jump on everyone but seem to lose it to the real fast guys on the hill-still have to work on the clutching or maybe setup to a bronco.

yeah it was 45.5hp- not bad with no head work

I've seen this Rhino and must say as a 700 owner it's impressive. Unleashed has done a great job with it. It made it up the biggest hills in Glamis and really performed well.

in your write up towards the end you say it runs better with the new crank and piston. is that a miss print and you ment new cam? iam getting ready to do mine and thinking of going with the 734 kit and a bronco clutch. i just want to make sure i can dune better and keep up with rzr's and make it up the big hills.

Is this a one stop shop process or would I need to take it to Weller as well?

Cost?

no it is a +5mm stroker crank- I dont think the bronco is going to help you that much with climbing the hills. it will help but the extra power from displacement is going to help more.

you would have to call and talk to Greg on that- as far as maping-depending if you have a msd and what exhaust I can help you out with what I have - again I would give Greg a call and talk to him.

Good write up but I think its time to put the mangina away and go riding, its not that hot. Perfect time to go to the lake with the easy up. swim all day and ride all night.

I wouldnt mind doing some late night hassi rides

what is the cost of what you have now. also don't you need more piston and head to size to increase it from 686 to 727. i didn't think just increasing the crank could increase cc's

The term 'Stroker' means that someone has increased the stroke of their engine. Displacement is determined by BORE (the size of your piston) and STROKE (how far that piston travels up and down). There are two ways to increase displacement: You can increase bore (with a larger piston), and/or you can increase stroke by moving the crank pin

so we've increased the stroke. You now have more power from the displacement increase, but you've also gained more torque. Why? Because moving that pin location outward on the crank is just like using a longer wrench to remove a stubborn bolt. You've given the engine more leverage. This allows the engine to generate power at lower rpm much more easily.

Another good thing about increasing the stroke is that with any engine that you plan on really going big, it makes more sense to increase bore and stroke, rather than just stick in a whopping large piston. In most cases, keeping the bore and stroke increases relatively equal, you will end up with a powerhouse that's more reliable and delivers power more evenly.

The problem with stroker cranks thou is you need a special piston in most cases. You can have a piston made that is shorter, or modify a stock piston. On minor stroke increases (totaling 2mm or less), you can sometimes modify the stock piston to fit. More than 2mm would require a special piston - that can get expensive unless you plan on talking 3 of your buddies into doing the same thing. OR you can do what I did and do a shorter rod so we can use stock replacement pistons- meaning we can find one anywhere.

Big Bore kits

Advantages:
Relatively easy
Changing just the cylinder and piston is easier than splitting the cases and installing a stroker crankshaft.
Cheaper than a crank, but not by much.

Disadvantages:
Head is not designed for that diameter cylinder.
Too large bore results in incomplete combustion
Too large bore reduces cooling jacket.
Larger piston adds stress to rod and crank.
Excessive vibration from heavier piston. Still need to remove crank to rebalance for heavier piston assembly. But if you do all that work, you might as well use a stroker crank.

Stroker Cranks

Advantages:
Stock Piston sizes are cheaper to replace and easier to get.
More torque
Better traction
Easier to control
Complete combustion – using head designed for this bore.
Longer stroke breathes “deeper” while valves are open.
Generally, better power than bore kits

Disadvantages:
If done poorly, can result in vibration
Very large stroke may require case modifications
Somewhat more expensive than big-bore kits.
Few companies can do it properly.