Dynojet makes a lot of performance kits for a lot of motorcycles. The Dynojet and K&N kits add torque, horsepower and try to fill out the powerband better.
I think they succeded with the Stage 3 jet kit for the XJ650R Seca.
I figure that it must be uncommon if not rare to install a K&N Performance Stage 3 jet kit on the XJ650, but I needed new needles anyways and the Kit was the best way to go, so I bought it and got it installed, setup and tuned professionally.
The stock XJ650R's engine felt "weak" in lower RPM's (the bane of In-line 4's lack of torque in low RPMs) and there isn't a lot of pull below 4,000rpm. From 4,000-6,000rpm you get a good shot of acceleration, from 6-7,000rpm the acceleration again isn't there and from 7,000+ you better hang on. So the seca engine is smooth all the way, but it just likes to squirt power out in weird ways.
The K&N Stage 3 Jet Kit, in case you are not familiar with it, K&N says: STAGE THREE KITS Intended for motorcycles with stock or mildly tuned engines using K&N individual clamp-on air filters and an aftermarket pipe. In most cases power increases of 10 - 15 % can be achieved. My kit came with 2 different sized jets 112 and 120, as well as new needles (with 5 positions, stock Yamaha ones are NON adjustable!), instructions with photos as well as 4 individual K&N filters and a K&N crankcase filter, they even had a hat in the box!
I helped the mechanic out (learning you know) as much as I could and watched a lot, here are my observations:
-It can be installed without the help of a mechanic, but I don't suggest it. Too much tuning, adjusting, setup, sync'ing the carbs and all.
-You HAVE to remove the air box, air box boots, air box hoses, filter.
-You need to "customize" a little the side panels so they fit better next to the outside individual air filters. You just need to shave the sides a little (you can't notice the change when its done)
-Need to do quite a bit of carb work, adjusting the butterfly valves, needle, air/fuel mixture screws etc.
-Need to test ride the bike quite a few times in different throttle, speed and gear positions to make sure everything is setup for maximum power and torque from the kit.
After it was all done (1.5 days), I have to say that the power curve of the XJ650R Seca is very strong all the way up to redline. The torque from the engine is VERY noticeably higher. It also cures the low-mid range lack of power! From 2,000rpm the bike pulls like it did without the kit at 6,000rpm. No more low RPM weak acceleration.
The individual filters make the whole bike just a little louder with a very sweet growl out of them the closer you get to wide open throttle (WOW). LOVE the sound, I'll have to tape it.
The modded XJ650R engine feels very strong and that is responsible by the K&N Stage 3 jet kit. Gone is the "squirty" power band, and it is replaced by a "hold-on" powerband that is smooth acceleration all the way without any noticeable deal zones. Another big improvment was from idle to 4,000rpm, the thottle was much more responsive, and there was acceleration and torque. (K&N Products: Stage 3 Jet Kit w/ Filter: 23-9021)
fortunately (or unfortunately depending on how you look at it), the K&N Stage 3 jet kit installation requires removal of the stock air box and boots. This allows the carbs to each get their own individual K&N pod filter as well as the crankcase getting its own filter as well. This is a very practical step to increase horsepower and torque as well as decrease weight.
The kit comes with different jets and needles to insert into your carburator to "hotrod" it. I noticed that the needles were MUCH better quality than the Yamaha stock ones and were adjustable in 5-6 steps for tuning. Dynojet also included 2 different sized jets too for further motorcycle engine tuning.
Starge 3 is an agressive kit designed for acceleration and performance. But Dynojet does carry stage 1 and stage 7 kits as well. A Dynojet Stage 7 kit is for the track and drag racing use only.
The kit lists for $129 USD. Money well spent IMHO.
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