Help Replacing the engine rod / pistone rod

sergman89 · Mar 2, 2015

So I ordered the lower F80 from thatsdax and realize now that my engine head is not the right size and the piston keeps hitting the top. In fact it stopped once the piston went to the top.

I have my old engine, which unfortunatly one of the top bolts were over tightened and stripped the bolt threading in the engine. However everything else is still freshly new and only used for maybe 10 miles.

Can I take the Engine rod/Crank rod/Piston rod from the first engine and put it in the thatsdax engine housing?

I just saw a video of Fred's take down, at this url ---> https://www.youtube.com/watch?v=kRAb-wLfTok , for the engine, but im not sure where exactly to get the extraction tool he used or what size it is. I have access to harbor freight and many other auto stores, so if you can please give some pointers and direction it would be appreciated.

MotorBicycleRacing · Mar 2, 2015

Why not get the correct piston for the bottom end?
Pistons are $10

sergman89 · Mar 2, 2015

Because I have both Piston sizes. The larger piston hits the bottom and won't turn fully.

Is it possible I may of messed something up or are there two different crank arm sizes? :-||

sergman89 · Mar 2, 2015

The weird thing is I thought I was making it rotate at first until I had to redo the wiring and chain tensioner and after that didn't work I tried checking the spark plug by putting it against the engine and rotating the wheel to see a spark.

However it won't do a full rotation and stops at the top so I couldnt.

MotorBicycleRacing · Mar 2, 2015

sergman89 said:
Because I have both Piston sizes. The larger piston hits the bottom and won't turn fully.|

There is no larger piston.

The difference between the 2 kinds of pistons is that one has a higher wrist pin location.

sergman89 · Mar 2, 2015

The original had kit came with the higher pin set up.

The lower engine from thatsdaxs is a low pin. Otherwise the piston bottoms out.

Does the crank arm not matter?

maniac57 · Mar 3, 2015

Yes the rod matters! You may have a "half-breed" engine...if noither piston works, clearly you have the wrong parts. But one WILL fit with proper mods.
Ask Mapbike about which you need....he seems to know all the different varieties quite well.

birdmannn101 · Mar 4, 2015

I know you guys are way above me in the technical field of engines so I won't jump in to this tread but "just a thought" now. . . Don't shoot the messenger. Would the spark plug be too long and is hitting the top of the head?

sergman89 · Mar 4, 2015

birdmannn101 said:
I know you guys are way above me in the technical field of engines so I won't jump in to this tread but "just a thought" now. . . Don't shoot the messenger. Would the spark plug be too long and is hitting the top of the head?

No the spark plug wouldnt be an issue. This bike ran before, with the same cylinder head. When I got the new lower engine it doesnt mesh with my engine top though.

I have to order an extraction bolt, I was hoping I could make or get one local.

Davezilla · Mar 7, 2015

If you got the 40mm crank bottom end and your piston has the high pin then it's going to hit the crank on the down stroke... Is this what you're experiencing?
The only real fix for this is to get a piston with the lower pin to get the needed clearance. Here is an example of the difference in piston pin hights... http://www.ebay.com/itm/MOTORIZED-B...SKYHAWK-AND-FLYING-HORSE-MOTORS-/281563273687 If your piston is hitting the top of the crank on the down stroke you'll need the cylinder and piston kit that's Model B in this listing, or the one with the lower pin hight if you buy elsewhere, if the piston is hitting the head on the up stroke then you'll need the model A piston or the high pin piston if bought elsewhere to fix your problem.
You'll also need the proper cylinder as well or the ports will be too high or too low for proper performance so you'll need to buy the piston and cylinder kit to make the engine work.
The same seller does sell these kits for $30 but they have the wider 40mm bolt distance intake ports that would also require a 40mm intake, other sellers have these same type kits with the standard 32mm intake bolt spacing.
Of course, if you bought a DAX bottom end it's probably best to just give Duane a call and he can set you up with the right parts to get you back up and running.

MadMaxed · Mar 7, 2015

The bottoms dax is selling is a type d if im not mistakened

http://thatsdax.com/ENGINE_KIT_PARTS_PAGE_3.html

Scroll down to the bottom. Like davezilla said Type b pistons fit these blocks. sorry for the echo. Duane And Grady will fix you up with what you need. I would have just bought the whole engine The sell

http://thatsdax.com/ENGINE_KIT_PARTS_PAGE_1.html

Would have saved time, money, and headaches.

.trk

sergman89 · Mar 7, 2015

I will buy their whole engine next time however this was a good experience.

Thatsdax.com has a few custom motors I'd like to try out on my next build.

MadMaxed · Mar 7, 2015

sergman89 said:
I will buy their whole engine next time however this was a good experience.

Thatsdax.com has a few custom motors I'd like to try out on my next build.

Im in love with dax motors never a lemon.!!

Davezilla · Mar 8, 2015

MadMaxed said:
Im in love with dax motors never a lemon.!!

Same here... I never have that "roll of the dice" feeling ordering engines or bottom ends from Dax... I'm also tempted to get one of those newer 38mm lowers and see what I can make it do, but I'm really happy with the 40mm lower I put on mine last summer, huge difference in smoothness and power capability.

MadMaxed · Mar 8, 2015

I gotta 38mm coming in the mail. I'll let u know how it runs

Davezilla · Mar 9, 2015

Yes... let us know how it runs... I know map just built one and says it's a really strong runner too.... I'll be buying more engines and parts over the summer months so I can build a few more bikes to sell during the winter months when my business slows down about 2 weeks before thanksgiving until about mid January. Right now there's just no time to build anything unless I stay at the shop after hours to do it, but in mid November until mid January people usually won't worry about getting their cars fixed until tax return season, but they will buy bikes for Christmas gifts etc...

MadMaxed · Mar 9, 2015

Davezilla said:
Yes... let us know how it runs... I know map just built one and says it's a really strong runner too.... I'll be buying more engines and parts over the summer months so I can build a few more bikes to sell during the winter months when my business slows down about 2 weeks before thanksgiving until about mid January. Right now there's just no time to build anything unless I stay at the shop after hours to do it, but in mid November until mid January people usually won't worry about getting their cars fixed until tax return season, but they will buy bikes for Christmas gifts etc...

Will do. it will be my first balanced crank motor im super excited.

Davezilla · Mar 11, 2015

I'm sure you'll be happy with it... the difference between my first engine and the Dax engine are night and day... and I push mine passed 10k rpm every morning with no vibration at the seat or bars... its even smoother than my sportster.

MadMaxed · Mar 11, 2015

Davezilla said:
I'm sure you'll be happy with it... the difference between my first engine and the Dax engine are night and day... and I push mine passed 10k rpm every morning with no vibration at the seat or bars... its even smoother than my sportster.

Nice I've been prepping by practicing port matching and such on an old jug. Beginning next week my motor will come in and i will be going to town literally.

MadMaxed · Mar 11, 2015

My problem with my last engine is i would let it sit to idle, it would start to rattle itself and scoot along the drive way.. pretty bad

Help Replacing the engine rod / pistone rod

New Member

Well-Known Member

New Member

New Member

Well-Known Member

New Member

Old, Fat, and still faster than you

New Member

New Member

New Member

New Member

New Member

New Member

New Member

New Member

New Member

New Member

New Member

New Member

New Member