Pump Gas Mull Engineering Head

[Strm Trpr]

So why are you on here asking for help them. He told you what to do.  Spend $119 get a little better usable power.  I didnt need to rejet.  im at 500-1000ft

WTF are you talking about?

 

First of all, who the fuck are you to question me about what my thread is about?

Second, I'm asking for jetting help because I'm installing all of this new shit all at once!!

 

33mm PWK's w/pods

UPP cross-over intakes

VF4's

Mull Pump Gas Head

PC's w/304 silencers

 

Sorry for asking for help in my own thread... fucking dick!!

[sheerider11]

So why are you on here asking for help them. He told you what to do. Spend $119 get a little better usable power. I didnt need to rejet. im at 500-1000ft

Are you fucking sniffing paint?

[Bennett131]

So why are you on here asking for help them. He told you what to do. Spend $119 get a little better usable power. I didnt need to rejet. im at 500-1000ft

Pretty sure he was more worried about you running +4 timing with the added compression than asking you for help.

[Strm Trpr]

Pretty sure he was more worried about you running +4 timing with the added compression than asking you for help.

^^^ Exactly!!

[edgehanger]

I got almost the exact same set up.

Fmf

K&n filter no lid with outerwear

0 timing mull pump gas head cut to 66.50. Stock porting

280 mains 30 pilot at sea level

Stock carbs.

Throttle response is outstanding.

Sun of a bitch is kicking at 175 psi though. Im running 93 pump gas until the engine tells me not too. So far no sign of excessive heat on the plug

 

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[Strm Trpr]

Dayum, that's high compression.
Welded crank?

[Oldskool83]

I was only saying if mull said it will help you get it.  I had all my mods done before I did their head mod.  Trying to get or set a bike up with out the parts is nearly impossibly, you can get close but every machine is different.

[edgehanger]

Yep crank welded. I'm kinda disappointed with the high compression. not what i wanted but the head was mucked up pretty bad so i guess mull had to take alot off to clean it up. Im seriously considering swapping it for a cool head with big bore domes. I really want it lower.

 

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[Strm Trpr]

Ahh

The head I gave him was clean and virgin.

I'm hoping I'm right around 155psi.

[blowit]

Hello, I ran into this thread and figured I would pop in.  Edgehanger, you might PM me with who you are are I can look more into it but just a couple things to note.  

 

1.  Cranking or kicking compression should never be the sole value used to determine fuel octane.  It has no bearing.  It might scare some but that 175psi with STOCK ports is about right!  

 

2.  Always let your engine tell you how much timing it wants, don't just go with an Inet value.  Creep up on timing making observations and plug checks.  

 

What you will notice is most here say "ah, you need that compression down around 140-150".  What you don't realize is most have at least mid level porting which drops the "cranking" compression and does drop the CCR, but does not drop the UCCR.  We look only at the CCR and UCCR when doing head volume targets.  If you take that same setup pumping up 175psi and apply an aggressive dune port, you are likely to see numbers in the 150s.  

 

Brandon

Mull Engineering

[edgehanger]

Thanks Brandon. I know the cranking compression doesn't tell me what octane to run like many here believe. The plugs look good and no signs of detonation. I just didn't want that much pressure on this daily driver play bike that's all. The head i sent was a POS and you did an amazing job on it. I've seen alot of "cleaned up recut" heads. This one is top knotch. I might still swap this head and save for a more special build in the future

 

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[Strm Trpr]

Well, I know this is frowned upon, but my bottom-end is stock and has never been opened up, therefore the crankshaft is not welded.

Cylinders are stock bore stock port too.

I think I might back the timing down to 0* advance for initial start-up with this new head and all of my other new mods so I can be sure the tune is spot on before adding any advance to it.

 

Anyone have any thoughts on this? Brandon?

 

First trip is to Pismo for Memorial Weekend and I'll be there from Friday to Tues.

 

Need the crank to stay together!!

 

I know 33's are overkill for a stock motor.

I sold my stock carbs and needed to pull the trigger on a set of PWK's.

33's and 35's are back ordered all over the country.

JD's distributor had these two in stock so I snagged them.

After this trip the bottom-end is going to Redline for some 421 Serval action!!

 

Mods for initial start up will be:

33mm PWK's w/pods and outerwears

48 pilots

airscrews 1/2 out

CEL needle middle clip

155 mains

0* Timing Advance

91 octane mixed 40:1 with YamaLube 2R
UPP cross-over intakes
VF4's
Mull Pump Gas Head
PC's w/304 silencers

 

Thoughts on jetting?

 

Will the left carb drain bolt head hit my clutch actuator arm with UPP intakes and VF4's?

[camatv]

need to get the crank welded  and checked ut  if its more than 6 years old and you actually ride the bike  its probably getting a tad loose..

 

just like anything and any motor build  as stated  get it all together  start the bike  jet from there.  check plugs for timing and jetting  maybe read the long jetting how to if your not to sure what to look for in the "tech " section..?

 

and always always check your squish band clearance when running one of these heads.  unless you did a deck height measurement and spec'd a squish height on each cylinder it might be to tight.. i know there will be some call outs on this spec but anything tighter than .052 and your loosing hp..  any band width more than 9.5mm and your hurting the motor..  just look at pics of the tops of domes and you will see the ring of heat that the wider band produces.  the piston will tell you how wide the band needs to be..  i have had 4 motors come over from wichita that this was one of the many things wrong with them.  im not going to say what shop built them but they have all been jacked up  i do know it wasnt MULL.  mull has some great products and great service..   running these specs witht he correct dome CC for the fuel and timing ou are going to run will result in a motor that lasts for as long as the other parts hold together.  and will run great... 

 

of course this is all my opinion from building motors that last and last for over a decade now... 

[Strm Trpr]

need to get the crank welded  and checked ut  if its more than 6 years old and you actually ride the bike  its probably getting a tad loose..

 

just like anything and any motor build  as stated  get it all together  start the bike  jet from there.  check plugs for timing and jetting  maybe read the long jetting how to if your not to sure what to look for in the "tech " section..?

 

and always always check your squish band clearance when running one of these heads.  unless you did a deck height measurement and spec'd a squish height on each cylinder it might be to tight.. i know there will be some call outs on this spec but anything tighter than .052 and your loosing hp..  any band width more than 9.5mm and your hurting the motor..  just look at pics of the tops of domes and you will see the ring of heat that the wider band produces.  the piston will tell you how wide the band needs to be..  i have had 4 motors come over from wichita that this was one of the many things wrong with them.  im not going to say what shop built them but they have all been jacked up  i do know it wasnt MULL.  mull has some great products and great service..   running these specs witht he correct dome CC for the fuel and timing ou are going to run will result in a motor that lasts for as long as the other parts hold together.  and will run great... 

 

of course this is all my opinion from building motors that last and last for over a decade now... 

 

Awesome advice, thanks Cam!!

Unfortunately I'm out of time to tear the bottom-end apart and have the crank welded.

I'm leaving for Pismo in 18 days.

I hope this doesn't kick me in the balls, but I'm gonna risk it!!

However, I will do a squish test like you recommended just to know what's what.

[Strm Trpr]

I did a squish test and both combustion chambers are right at .054".

I did a cold kick compression test today and both cylinders are 150psi.

I backed timing down to 0* to tune.

Do you think it'll be safe to crank the timing back up to +4* with the above compression and 91 octane?

I'll add timing after I dial in jetting.

When adding timing what are signs of too much timing and how do I test it?