mods for better mpg

[CA ExhaustCoatings]

Originally Posted by mikehallbackhoe

I am running my own home built design exhaust system, basicly a 6 into 2, with a crossover tube. my valk is a 98 calif. tourer, desmogged, and fed. heads and cams installed. also threaded the intakes, and added grooves to the combustion chambers. I will try the shocks set at #3 and see how that feels.I don't remember the brand of thermostat, bought it at napa. I have tried more ignition advance, but had problems with pinging.

Calif. bike, u have the better mpg cams. everything else about the engine is the same as 49 state. According to some all 98 models have the calf. cams also. The desmog did nothing for mpg as u already know, except the loss of about 5 lbs.
Threaded intakes, are u talking intake manifolds or intake ports of the heads?
I polished my IMs to 320grit picked up 1-2 mpg.
Napa is usually a stant. thanks
what type is ign advance? the engine doesn't like more than 9 degrees intial.
u might have been pinging due to the cam advance and/or the cross over leaned u out causing the leaness. crossover leaness noted below.
http://timskelton.com/valkyrie/tech/...s_dyna3000.htm
I have a set of true headers from viking exhaust that I have to ceramic coat and install. Others are picking up 2 mpg with them with no other changes.
tell me about the grooves in the heads? how much gain? thanks

a post of mine. It seams that at hwy real world rpms a crossover does nothing. I have read other articles that a simple cross over really doesn't work with a 6 cyl, only with a v-8 as shown below.

http://www.valkyrieforum.com/forum/tech_archive.cgi
Posted By: 98valk <fitness7days@nospam.juno.com>
Date: 2/8/2005 at 17:44:40

In Response To: CROSSOVER option available (MarkT)

per a 11/91 circle track article, a same size crossover as the collector and in the case of the test was 3 1/2" provided the most torque in the 4500 to 5000 rpm range. no crossover the least torque. However no cross-over provided the best torque 3500 rpm and below although the 3 1/2" was not far behind, however in the 6000 to 6500 rpm range no cross-over made the most torque by a wide margin compared to the crossover. HP figures reacted the same also. As usual no free lunch. But, when using a crossover 1 inch smaller in this case 2 1/2" bottom rpm range was almost the same as no crossover, upper rpm range was also almost if not the same and in the midrange was only down about 5 lbs-ft. The 3 1/2" made 18 lbs-ft over no cross over. HP again follow the same pattern. Their testing also showed that the crossovers also leaned out the air/fuel ratio from 2 1/2" 13.0 to 13.5, 3" - 13.6 and the 3 1/2" - 13.4.
So to see a difference go one inch smaller than the collector and it looks like a re-jet on the mains would be in order or a Dial-A-Jet.

[mikehallbackhoe]

I have tried both cams, and prefer the fed cams for power. haven't really noticed a loss of mpg. I threaded the intake manifold and the intake on the heads, and added a single somender groove on each combustion chamber. I have read several articles stating a crossover improves lowend torque. I designed mine to be removed if needed. might try it without and see if I notice a difference.

[CA ExhaustCoatings]

Originally Posted by mikehallbackhoe

I have tried both cams, and prefer the fed cams for power. haven't really noticed a loss of mpg. I threaded the intake manifold and the intake on the heads, and added a single somender groove on each combustion chamber. I have read several articles stating a crossover improves lowend torque. I designed mine to be removed if needed. might try it without and see if I notice a difference.

did u notice any difference with the mpgmike mods? have u done any airbox and carb rejetting?

[mikehallbackhoe]

can't say I noticed a big change in mpg. too many variables in riding conditions, and too many changes at once, but I believe the grooves make a faster burn, which could effect timing.I haven't changed jetting, or modified the air box, other than routing fuel tank vent into bottom of air box. I am sure I am running lean. riding two up, took a trip to the coast the other day, running 65- 70 , averaged 41 mpg. I am considering adding a water vapor system, heating the water with exhaust. if I use the throttle cable to operate a cable operated shutoff at idle, possobly a small carburetor, I could control how much steam I put into the bottom of the air box.

[CA ExhaustCoatings]

Originally Posted by mikehallbackhoe

can't say I noticed a big change in mpg. too many variables in riding conditions, and too many changes at once, but I believe the grooves make a faster burn, which could effect timing.I haven't changed jetting, or modified the air box, other than routing fuel tank vent into bottom of air box. I am sure I am running lean. riding two up, took a trip to the coast the other day, running 65- 70 , averaged 41 mpg. I am considering adding a water vapor system, heating the water with exhaust. if I use the throttle cable to operate a cable operated shutoff at idle, possobly a small carburetor, I could control how much steam I put into the bottom of the air box.

that's a great avg at that speed two up. that's in the mid 50's mpg straight hwy IMO.
is your car tire larger dia that stock mc tire?
do u know that the last few yrs of the GW GL1500 gears will go right into our bikes? The GL has a higher OD ratio. A lot of work though to split the cases esp of a 230lb engine. I always think one day I want to do it or just swap in a GL engine and use the existing heads and carbs from my bike.

[mikehallbackhoe]

my rear tire is a 205 60 16, same diameter as stock tire. most of my riding is in the mountains, at speeds of 55 or less, so an overdrive isn't really needed. if I wanted higher gearing ,I would opt for a 65 series car tire, much easier and cheaper than swapping gears. I swapped out the cam gears from a gl1500 and they were slightly advanced compared to the valk gears.

[Jim T.]

Originally Posted by mikehallbackhoe

I only accomplished 54 mpg once, while sedately cruising the back roads with two old couples ,riding a goldwing and a boss hoss trike. but I consistently get 45 mpg, 55 mph, 2500 rpm. riding in the mountains. oh, I also run a 205 60 16 general altimax car tire on the rear. by the way your specs are for an interstate, I run a tourer, which is lighter. I also noticed that my mileage is better than all your vehicles except your scooter, so my efforts of obtaining better mpg from my valk may not be a moot point after all

Never argue with cat0200. All you will get is the "my sheetbox chinese POS is better than" (insert whatever you ride here) "and you better go buy one or you suck, and the earth will cease rotation immediately" reply.
You'll wind up with a headache, and he likes arguing about ANYTHING.

Jim T.

[mikehallbackhoe]

I recently left a motorcycle forum because of that very reason. I am searching for information, and don't mind debating what works or doesn't work, but I am tired of dealing with people who just want to argue. I enjoy my motorcycle, and wouldn't trade it for any other bike, but at the same time, I love to modify and tinker with my ride. one nice thing is that it does not have any fancy computors that make it difficult to experiment with things. while the valk is ideal for my wife and I, if I could have another bike just to experiment with, it would probably be a suzuki 650 savage single. very simple to work on, and capable of getting great mileage.

[michaelwoodcock]

Hey man, whats your mileage up to now?
I will tell you a few things that have worked in my past experience.
My experience =









things that help:
1. exhaust
2. gearing
3. CDI

4. tune!!!!! A well tuned motorcycle will trumph a poorly tuned bike any day. Forgive me, I am unfamiliar with the honda valk. But, is it fuel injected? if so, a power commander with a very small fuel cut would help. It is probably not throttle by wire (which can be programed with a kit) if it's carbed, you could maybe get away with lowering the slide needles a touch to decrease acceleration gas used.

5. tires!!!!! I don't suggest running highly increase PSI on the front. You would still want stopping power. I have in the past noticed a 2-10 percent increase with slick, slim, higher PSI tires. Check out the pirelli sl 26's to get an idea of what I ran. I ran those on my honda ruckus, at 44 psi. It was perfectly safe, because the drum brakes coudn't overwhelm the grip of the tires at that PSI.

The stock honda ruckus can get 80mpg or more, I got over 90 with variator, the tires, CDI, and a different (more conservative) carb needle. Not to mention, a 47mph top speed.

Ideas of yours I like:
1. windscreen. You could do a coast down test to find the best config! (just an idea) if you don't mind spending a few (or a lot) of $, you could get a veypor 2 (VR2) gauge to calculate these tests for you.
2. The gas tank vent re-routing. WOuld deffinatly help with a fuel injected bike that has an o2 sensor, not sure about the valk though. Is it fuel injected?

if it is carbed, be sure to tune it to run stoichiometric (14.5 to 1) on hot air! that would help out right there!!! if you need some jetting advice go to carbtune for CV carbs, or google it for slide carbs


Oh yeah, you can put a shim on your carb spring if it is a CV carb. That'd help!

[mikehallbackhoe]

the valkyrie has six carbs. the good news is ,it is so smooth, you don't have to worry about the carbs needing adjusted, they stay in tune. I have considered hot air, but have no way to route it to the airbox, have considered heating the fuel though. when it comes to tires, I don't mess around with high pressure, safety comes first.