1998 VZ800 Stage 3, final configuration and graphs.

I bounced between lean and rich , but it's right there on the money now , the jets sizes so close I can call the optimum by chosing the middle ....

I've put a summary below.



1998 VZ800 Modified to Stage 3

The pilot system required no modification , and at time of writing, no reason to displace the (new) needles E-clip either up or down from the middle position, could be found.

Presentation of "Before" and "After" performance curves provides defining and valid proof of the performance gain.

Test Bike :

Vin JS1AF111500100405 , series VZ800"V" ,assumed 1998, 7th owner or more !
Engine Number S506125843
Odometer Approx. 21 000km
Altitude: Coast , 10m MSL
Conditions: 15-25 deg C , Cape Town , sunny South Africa

"Before" condition:

Bone stock , Full-Throttle switch found and remained connected , no "PAIR" system existed , the 98 model is characterized by the rear cylinder header routed around the base of the engine, and not around the back of the cylinder. The only departure from OEM original was a pair of exhaust end cans with internal dia of the baffle tubes in the order of dia 24mm , through-flow. The 'before' run was compromised, by one of these baffles getting lost en route to the dyno. As the stock clutch was already showing signs of slippage , the clutch was disassembled, the steel plates deglazed with 800 grit waterpaper , new OEM friction plates where installed , but the original springs were replaced with high performance Vezrah units , SK329 , a very common fix. Lever effort is obviously increased. A wise man very accurately sets the valve clearances about now !!! Engine oil was Putoline 20W50 mineral , used generally for hot summers , 10W40 is prefered for winter and the recommended viscosity grade by Suzuki.

After the "before" condition was dyno'ed , I had two new 38mm core baffles hand made , which became therefore, part of the "After" condition variables. This could have had a small influence on the main jet selection, but by < 5 'units' , is my guess.

Parts Required:

K&N filters, 1 of RU0680 for the front , 1 of RA0470 for the rear , which includes a plastic elbow
Mikuni Carb Needles 2 of , both "5DP7"
Vezrah Clutch Springs SK329, & Suzuki clutch cover gasket 11482-48E01
Mikuni Main Jets ... depending on baffles diameter mainly, recommended, almost certainly optimum, or very close start point ... 142 front , 145 rear
A roughly 12mm slice of any old 2" ( 50mm ) PVC pipe fitting , to fit in the front filter mouth...from your pool shop, plumbing supplies, or shed.
A new or good condition 2.5mm drill bit

Work required:

It is assumed you are competent and have a little experience , essentially, get the carbs loose and free but keep the cables attached, extract the airboxes and bid them farewell by recycling what you can. Replace them with the air filters , but I recommend you first bend the old mount tab on the right side of the frame at the front, out of the way of the new front filter, or it will chafe it. You will lose the cable securing mount for the same reason, carefully applied cable ties will do the same job. Loose the metal tab or it will chafe the filter.

The rear filter and it's elbow punnched through the rubber, can accommodate the old crankcase vent piple, with thought. Not quite positive crankcase ventilation like before , but better than being open to atmosphere.

Open the carb bowls , if you are smart , use "Hexagrip" on a clean screwdriver ...it increases the friction between tool and screw head by some 500%...you may need this, they are tight, install the 142 on the front (replace the 90), the 145 (replace the 100) on the back, close up. If you don't have Hexagrip , try course valve lapping paste.

Open the carb tops , remove the 5C29 (F) and 5D27 (R) original needles, note very carefully what you are doing, and the orientation of the retainer plates ! Drill both slides vacuum holes to 2.5mm all the way through. Only a little material is removed, this is correct

Install the E-clips on the middle slot of the 5 slots , of the new 5DP7 needles , ( thank you Grant STL over in the USA ! )

Now, be very, very attentive ! Needle pointed sharp end down ...E clip in the middle slot....push the plastic spacer up from the bottom so it's now UNDER, not over, the E-clip !!! Then the small metal washer, then the spring.

You now have, from top to bottom, e-clip, plastic spacer, metal washer, spring. Yes, nothing UNDER the e-clip has any effect on the needle height ! But it does STABILISE the needle in the slide. Put the needle in the slide, replace the retaining plate to push it all down, make sure the needle is centred, and tends to snap back to centre if displaced to the side. Are you SURE ? It's free yet self-centering? Yes ?

Replace the carbs with care , be very careful with the choke cable, you will see what I mean.

The slice of PVC pipe fitting should make an ideal internal re-inforcement INSIDE the front K&N mouth , so you can clamp the link pipe firmly ... you will understand when you see how it needs to be employed.

With the bike painstakingly assembled , the carbs sync'ed , and the idle mixtures dialed in , you are done.

It should ride without missing a beat , behave like a stock bike off idle at part throttle , then accelerate like a bat outta hell at larger throttle openings.

The honk of those open airfilters will let you know you're now riding a very modified beast , you'll get used to it in time.

Be warned, it will most time wheelspin in 1st given a heavy hand ...

What an excellent write up

Nice write up John I love the last line! New rear tyre will be the next mod then

Excellant write up,thanks for sharing.

Brilliant write up and explanation of the charts. I am sure that will come in very usefull to someone.

This is awesome info and I am absolutely doing this next month after the semester is over!

Hi Guys

My mods are still working and working well ....

Some things you have to share, forgive me please ! It's this badass bike you see ... 

Veemax down under in Cape Town, celebrating SPRING !!!!

Again I love the mod you have done and the bike looks brilliant, glad everything is still in shape and working as it should be. Your bike is a real winner for sure, looks like a muscle bike in the way it is setup. Badass bike as you say, for sure.

Smoking as the kids around here say. 

ride it like yu stole it hee hee hee

Nice burn out! 

Ha Ha thats what I was thinking but didn't write it.

Great write up John - very informative & lots of food for thought.

Great bike you got there too ! 

  Yam

An amazing write up Sir, very well done indeed.

Some pics from a 1000 mile ride in August , this mod works and works WELL , I am getting 21 km per litre on the open road, yet at full bore it's still da BEAST ! All is so stable I forget the bike is completely violated.



Eat yaw heart out those who live on that crowded little soggy island , I may be the victim of a weak currency but there are compensations ! *grin*

Anyone confused as to why the "tissue box" is on the right side of the motor, well , my wife and a friend were carrying my luggage , but I had a wee bottle of Brandy in there for the desert cold .....

Cool pics John   

Just finished the stage 3 on my marauder. I cant say enough on how well put together this post is. I followed it to the letter and everything went very smoothly. Got the bike back from the local bike shop for carb sync and to get all of the cables adjusted properly. They were very sceptical of the mod i did until i came back to pick it up and they said how impressed they were on how well it ran and how easy it was to get dialed in. They ran it in the shop and it ran great untill they pushed the choke in and picked up the rpms. It started popping thru the front carb and they told me it just needed to warm up and pulled the choke out a little and it went away. Unfortunatly it was pouring rain when i picked it up so i couldnt ride it for a few days after picking it up. When i took it out almost immediately it started popping thru the front carb and missing on the front cylinder. I reached down and pulled the choke out thinking it may have still been cold and it went away but after 20 min of riding it was still doing it every time i pushed the choke in. Was wondering if you or anyone else has had this problem and what to possibly look for.Thanks

Hi Oregon Marauder. Wow, not been here for probably a year. Got an email notification. I think you can cure your popping problem with half a turn out on the front carb idle mixture screw. It sounds simply like the idle mix is too lean, and it's probably quite cold , with associated dense air, where you live , right ? Give it a go, I'll be on standby here to offer further help. Go a three quarter turn if half doesn't cure it. There is no substitute for the warm-up behaviour , to give you solid data on the idle circuit. If you still need choke beyond 2 minutes of warm-up, it's too lean, if it goes off-choke with no popping within 10 seconds, it's too rich. ( kinda ! ) , good luck, your problem is hopefully a tiny one.

great to see you jump back on the site to give advise to others in need John

Got to say I have missed your pics of ya disappearing in to the distance with a long black line of your tyre left on the road