How does it run?
Are you running pump gas?
With the stage one hotcam could I get away with 11:1 on pump gas?
With the bike being brand new, less than 1000 miles, could I get away with just honing or should I go up to the next bore size?

This is the last thread I'm gonna post about this, maybe i was asking the wrong questions before, but hopefully everything gets cleared up this time.

Edited by Page Mohler, 24 May 2012 - 11:14 AM.

What Octane pump gas can you get???

I can get 107 octane leaded fuel from a pump at a nearby gas station.  It would be "pump gas" and handle it no problem, even blended with some unleaded .  Does your fuel have alcohol in it?

I would avoid a Hot Cam and get one by Cycle Wizard.  He will set you up with a better grind and can get 10.5:1 to run on 93 octane fuel.   He can also make any piston you want.  His HRC+ version cam is a slightly more aggressive grind then the HRC628 cam Honda sold as part of the power-up package for the XR600R.  It's probably right for your desires.

I would add a pumper carb first IMO if you don't have one though.

I'm sure I can get race fuel somewhere but 91 is the highest at any pump around here.

As i posted in the other thread......you can get a 100mm 10.5:1 piston.........but it may NOT fit the bore properly,i am a mechanic,,,,,,,if the piston is tight in the hole the cylinder can be honed to fit the 100mm piston........if the piston ends up being loose before honing it`ll rattle,,wear fast,,possibly break a piece off the skirt of the piston...the only way to know for sure is buy the piston at 100mm and take it and the cylinder too a machinist and have him measure both parts..he can tell you if it`s possible or not.......

But like i said,,,,,if it`s going to be too loose and he says no.......then you may have a problem returning the piston after the box is open...

The hotcam in this engine can be problematic.....i`ve seen at least 5 that ate the rockers,,,either the cam was faulty (these are made in china) or the owner did not set the clearances properly...

The cam i have is the CW HRC clone cam,,,,he welds up your OE cam and grinds it too HRC specs.....it is a little noisy...but a highlift race cam is not going to be as quiet as the OE cam..

You will not have a problem with a 10.5:1 piston with a good cam.........lots of people use them..

PM MCMA111 on advrider....he`s used a ton of Wiseco 10.5:1 pistons in SF heat with no issues...

With the set-up i have i can wack the throttle after being in second gear and this thing will just scream and wheelie.......first gear is kinda scary as it tends to wheelie to easy for my liking.....i can imagine that 14/48 gearing on my bike would be funny as hell..lol..




B

Edited by brianhare, 24 May 2012 - 12:43 PM.

I have that setup and love it.  No problem on Premium gas in our weather. Very strong running XRL.  

Hey brianhare thanks for all the advice man.
I figured it would have to at least be honed but am hoping it won't have to be bored, that's why I'm trying to hear from other people running this setup cus they can tell me how their engine is running without boring it out.

Mindblower did you just have the cylinder honed?

Edited by Page Mohler, 24 May 2012 - 02:59 PM.

TNTsXLR, on 24 May 2012 - 11:32 AM, said:

+1 but I think it is important to note that he will probably end up doing both at some point... pumper first then he will want higher compression and aftermarket (or re-welded) CAM..

Now Page it might be easier to get feedback on the higher compression with an over-bore... just my opinion but I feel like you're in a unique situation buying a "new" bike and wanting to rip off the cylinder and get higher compression..

All I mean by this is I would think it will be hard to find guys here who actually took your path (or even could) in just honing the stock bore and putting in higher compression piston.

I feel like it will be much easier to get opinions on 101mm or 102mm pistons w/ aftermarket CAMs..


Yea I can resonate that it will be like 80$ more to get the bore.... AND you will be up to the 101mm with only the 102mm left for the future.... but the cylinders can be re-sleeved and you might like the extra 10 or 20 cc's for the extra 80$

It is all trial and error getting the "perfect" setup and even if you find someone with a "working" "great" setup, these are just mechanical parts and each one itself is unique and even if you assemble and install correctly there are the cases where these parts fail (i.e hotcams chewing rockers). Doesn't happen all the time, but certainly has to many people

If the cylinder is from a new engine I would send it CW to be honed and he will make sure your clearances are correct.

I would get in contact with CW since he is a very experenced XR engine builder and has all sorts of sweet mods from cams and pistons to stroker cranks and custom rods.

His big fin head with some porting will keep the engine cooler, help prevent ping and make the most out of the new piston cam combo.

An oil cooler would be a must have mod also IMO.  An NX650 2nd gear is a great mod to do also.

Done right you'll have great reliability and wicked power too boot.

Alex DeFreitas, on 24 May 2012 - 04:16 PM, said:

What you just said is making me lean towards what i want to do which is keep the stock bore.

I'm about the farthest thing from an expert on building engines... but i would think that because my cylinder is brand new it should fit perfectly.
I guess there's no right or wrong answer and it really would be a roll of the dice...

Page Mohler, on 24 May 2012 - 05:01 PM, said:

In theory I would completely agree with you.. in theory lol. these things are never definites i dont think...

Page Mohler, on 24 May 2012 - 11:10 AM, said:

Page Mohler, on 24 May 2012 - 11:10 AM, said:

For the sake of god man why do you want to use a Hotcam in your new motor mate????????
And no you can't run a hotcam and 11.1 on 91/92 pump gas you need at least a 106 LSA and 270 duration@.050 and .380 lift

The reason you need .380 lift is to accomplish the .270 duration...
If you want I can show you 100's of hotcams that have taken a dump on these motors, you need to mod your topend oiling if you want any life out of that cam..and I'm not talking 8 or 9 thousand miles I'm talking about 40,000 and up.
Do it right the first time or do it twice..

Give your motor specs to a custom cam grinder it's not anymore money and you get to keep your auto-compressor...talk to Brian and all the others that have bought a custom cam from - - - - - - - - and ask them what they think about a hotcam vs a custom cam..

Why would you do that to your new bike?????????

cyclewizard, on 24 May 2012 - 05:46 PM, said:

+1  

i have a 100mm bore w/ 10.5 je, hotcam stage 1 and have had no problems with cam or rockers for 3 years plus. substantial power increase too. just luck? i honed the stock bore slightly also. the reworked stock cam does sound like good insurance though.
garthr

garthr, on 24 May 2012 - 07:43 PM, said:

Yea maybe I'll look into a different cam but I've read both good and bad about that Hotcam. Hopefully when I end up doing all this I end up with similar results as you.

None of the flattop pistons will give you over roughly 10-1 TRUE compression. You need a reconfigured chamber and/or popup style piston to get anywhere close to 11-1. The Hotcam, flattop piston, carb andpipe will give about 10 hp over stock. Cheap. a regrind cam can give double that for considerably more money. Do whatever you can afford.

garthr, on 24 May 2012 - 07:43 PM, said:

How many miles does that equate to? just askin......    I've dynoed a hotcam and flat top JE and then did the same with the HRC628 cam and there's a large increase in power over the Walmart Chinese cam.
I think the walmart cams have quality controll issues some are good and others are not..but your leaving a good amount of power on the table by using one.
CW......

Edited by cyclewizard, 27 May 2012 - 04:10 AM.

valvesrule, on 24 May 2012 - 09:39 PM, said:

Do they really advertise these things that wrong. Even an 11:1 barely gives you 10:1 compression?

Edited by Page Mohler, 25 May 2012 - 05:30 AM.

cyclewizard, on 25 May 2012 - 04:28 AM, said:

+1 that's on the same trac as what I was touching on... things like creep, fatigue life... nothing lasts forever but some machined parts are plainly not designed to last for  thousands of miles... :sigh:

cyclewizard, on 24 May 2012 - 05:46 PM, said:

what units are these in?? and is lift the maximum vertical distance of each lobe over the center of the CAM shaft???

is duration in radians...?

Edited by Alex DeFreitas, 25 May 2012 - 08:24 AM.