Pumpkining my '05

BugR · Jun 27, 2007

I've heard it reported several times that one can replace the rear pumpkin on an FJR with one from a Gen 3 Royal Star Venture.Previous Thread

The benefit of this is to lower the engine rpm by about 9% (3.66:1 vs. 3.33:1) and moves my cruising rpm down from 4000 rpm to 3640 rpm which would be perfect for the long haul to WFO this year.

I'm not really worried about the loss of power there are 5 gears in the box and I can always swap the unit back.

I have never seen a write-up for this though so I thought I would give it a try.

Step 1. Finding your unit

Easy way : Order a 4XY-46101-00-00, REAR AXLE GEAR CASE ASSY ( as per MNFJ05) ($587.51 US before shipping)

Hard way: Look for a second-hand one

Three weeks on ebay and my searches keep throwing up '83 Ventura Royale units. THESE ARE NO GOOD. '86 or up only ( as per MNFJ05)

Fed up with the ebay results (My guess is the V-max guys are buying them all), I started Googling and located a second hand unit from a 2001 Royal Star Venture from these guys Cycletherapy.com.

Well it's on order ($270 shipped) .....tapping fingers .... sigh, you always have to wait ...

Chris

05fjrBluedevil · Jun 27, 2007

BugR said:
I've heard it reported several times that one can replace the rear pumpkin on an FJR with one from a Gen 3 Royal Star Venture.Previous Thread
The benefit of this is to lower the engine rpm by about 9% (3.66:1 vs. 3.33:1) and moves my cruising rpm down from 4000 rpm to 3640 rpm which would be perfect for the long haul to WFO this year.

I'm not really worried about the loss of power there are 5 gears in the box and I can always swap the unit back.

I have never seen a write-up for this though so I thought I would give it a try.

Step 1. Finding your unit

Easy way : Order a 4XY-46101-00-00, REAR AXLE GEAR CASE ASSY ( as per MNFJ05) ($587.51 US before shipping)

Hard way: Look for a second-hand one

Three weeks on ebay and my searches keep throwing up '83 Ventura Royale units. THESE ARE NO GOOD. '86 or up only ( as per MNFJ05)

Fed up with the ebay results (My guess is the V-max guys are buying them all), I started Googling and located a second hand unit from a 2001 Royal Star Venture from these guys Cycletherapy.com.

Well it's on order ($270 shipped) .....tapping fingers .... sigh, you always have to wait ...

Chris

Well, I think this will be a good thing to keep an eye on, please post of pictures with your write up when you change it out and how it affects you ride, mileage etc.... Thanks Mike

FJRMGM · Jun 27, 2007

after reading the original thread I tried to find a new pumpkin also and did via e-mail but the seller (salvage yard) would not quote me a price over e-mail so I dropped it.

I would be interested in your results. A $270 part represents nearly 5,000 miles of gas money travel on the FJR so it has do be better than "it helped a little".

Mike-H · Jun 27, 2007

BugR said:
I've heard it reported several times that one can replace the rear pumpkin on an FJR with one from a Gen 3 Royal Star Venture.Previous Thread
The benefit of this is to lower the engine rpm by about 9% (3.66:1 vs. 3.33:1) and moves my cruising rpm down from 4000 rpm to 3640 rpm which would be perfect for the long haul to WFO this year.

I'm not really worried about the loss of power there are 5 gears in the box and I can always swap the unit back.

I have never seen a write-up for this though so I thought I would give it a try.

Step 1. Finding your unit

Easy way : Order a 4XY-46101-00-00, REAR AXLE GEAR CASE ASSY ( as per MNFJ05) ($587.51 US before shipping)

Hard way: Look for a second-hand one

Three weeks on ebay and my searches keep throwing up '83 Ventura Royale units. THESE ARE NO GOOD. '86 or up only ( as per MNFJ05)

Fed up with the ebay results (My guess is the V-max guys are buying them all), I started Googling and located a second hand unit from a 2001 Royal Star Venture from these guys Cycletherapy.com.

Well it's on order ($270 shipped) .....tapping fingers .... sigh, you always have to wait ...

Chris

So.....can I watch?

.....

Geezer · Jun 27, 2007

Hmmm, after reading the title of this thread I was expecting pictures of an FJR painted orange. B)

staledonut · Jun 27, 2007

Since the speedometer's input is from the engine/transmission instead of from the front wheel, might the speedo be thrown off by ~9% from the different ratio?

V2Neal · Jun 27, 2007

A Speedohealer aka yellow box should fix any speedometer errors right?

Intersted in hearing how this goes.

vectervp1 · Jun 27, 2007

Hmmm... I'm wondering how much more top end this will give you.....

Archer1022 · Jun 27, 2007

I'm definitely interested in how this works out. I never understood why Yamaha didn't give it a 6th; it has the torque to simply loaf along at 100+.

Archer

BugR · Jun 28, 2007

staledonut said:
Since the speedometer's input is from the engine/transmission instead of from the front wheel, might the speedo be thrown off by ~9% from the different ratio?

Not sure that's true for the ABS models (Mine is an ABS).

The speedhealer site indicates that for the ABS FJR's that the speed comes from the ABS system.

That's one thing to find out.

Chris

FlyingLow · Jun 28, 2007

This is interesting stuff

.

We're assuming that your existing drive shaft will plug right in, and the drive splines will mate up correctly to the driven splines on your rear wheel?

Absolutely I want to hear how this turns out, and hopefully with success.

The only downside to shaft drive is you can't revise gear ratios, unless you're an innovator.

staledonut · Jun 28, 2007

BugR said:
staledonut said:

Since the speedometer's input is from the engine/transmission instead of from the front wheel, might the speedo be thrown off by ~9% from the different ratio?

Click to expand...

Not sure that's true for the ABS models (Mine is an ABS).

The speedhealer site indicates that for the ABS FJR's that the speed comes from the ABS system.

That's one thing to find out.

Chris

I'm curious as to from exactly where the FJR's speedo get its input (I know, RTFM). After washing my 05 ABS, I've sometimes "spun dried" the rear wheel by spinning it up a little on the center stand (never above 5th gear

) and noticed that the speedo operates so it's definitely not getting its reading from the front wheel. If the 05 ABS's speedo gets its input from the ABS system, pulling the rear ABS sensor from its housing should confirm this.

BugR · Jun 28, 2007

FlyingLow said:
This is interesting stuff .We're assuming that your existing drive shaft will plug right in, and the drive splines will mate up correctly to the driven splines on your rear wheel?

Absolutely I want to hear how this turns out, and hopefully with success.

The only downside to shaft drive is you can't revise gear ratios, unless you're an innovator.

That's about it the only other killer issue is if the unit is a different thickness and the rear wheel doesn't line up.

This is a known farkle for the Vmax so if it doesn' work I have a number of Vmax'd mates who are interested in taking the pumpkin off my hands.

BobbyBlue · Jun 29, 2007

Should this only be attempted around Halloween ?

Keep us posted...maybe this is our 6th gear eh?

Blessings,

Bobby

radman · Jun 29, 2007

BobbyBlue said:
Should this only be attempted around Halloween ? Keep us posted...maybe this is our 6th gear eh?

Blessings,

Bobby

Keep in mind how fast this bike will idle along in first with the original ratio final. Gear ratio changing always has unintended consequences, while the higher final drive will improve highway cruising, in town rideability, especially in traffic, will suffer. there are always trade-offs when doing something like this.

PapaUtah · Jun 29, 2007

1st through 3rd gear are minimally affected when the Venture gear installed. Most noticeable difference is when you shift into 4th and 5th. You can tell you have a shorter gear in the rear. Gear case, swingarm to axle distance, thickness, splines, etc. are all the same in this case since 1986. Yamaha simply went to the parts bin for the rear end in the FJR. VMax folks have swapped into Venture gears for years. Venture owners who tow a trailer often swap for VMax rear gears to improve towing performance.

BugR · Jun 29, 2007

Just got notification that the pumpkin is sitting at the UPS store in Ogdensburg,

A quick scoot down across the border is in order for tomorrow.

Chris

SkooterG · Jun 29, 2007

Interesting stuff. Will look forward to hearing how things go.

First I heard of the speedo going off the abs components. I thought ALL FJRs got the speedo input from tranny output. Anybody knowledgeable and clear on this?

radman · Jun 29, 2007

Gen 1 bikes, ABS equipped, have the same speed sensor as non ABS bikes, in the same location, and functioning in the same manner. The ABS system calculates wheel speed, chassis speed, and rate of speed reduction based on the wheel speed values provided by the wheel speed sensors, and acts independently of the engine mounted sensor. The speed sensor located at the rear of the engine case functions as it would on a non-ABS equipped bike. The instructions concerning speed sensor throughput via the ABS computer apply only to the 2006 (Gen 2) up FJR, therefore are not an issue with Bugs (Gen 1 2005) install, and may not even be an issue concerning final drive ratio changes with the Gen 2 A Model bikes. All bets are off with the AE model, but a workaround is always possible with enough research.

Pumpkining my '05

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