Tuesday, December 27, 2016

TAT 2017 Post 8 12/27/16

Another modification update for my 2016 KTM 350 EXC-F Dual-Sport.

In my last post I explained how I removed and shipped my struts and rear shock to KTMWorld to be upgraded with heavier springs, re-valved and lowered 2”. They arrived safely at KTMWorld and will be worked after the holidays. I hope to get them back sometime in mid- January. BTW if you plan on doing this to your KTM, I had a UPS shipping office pack my items with the final weight of 35 lbs and shipping cost, including $3,000 insurance, of $228. Nobody ever said upgrading a dual-sport was cheap.

With my bike in a pretty stripped down condition for the next month or so I decided to incorporate a few mods that I found on the BestDualSportBikes.com web page (referenced as BDSB in this post). They are changing their name to KTMandHusky.com but this is a great site if you have a KTM dual sport.

BDSB has focused on upgrades for the KTM 500 EXC-F but also have them for the 350 EXC-F. I ordered, received and installed this week-end several of their modifications described below and have 2 more on order.

Sorry if this post gets a bit “wordy” but I hope my experiences descried in detail below saves others trying to figure how to install these modifications.


Emissions removal kit

This kit includes several items to plug holes in the various parts of the engine as you remove all the plumbing and emissions hardware. Most of the items come off easily except for the air valve attached to the front of the engine. On the KTM 500 this valve is on the right side and easily accessible. On the 350 it is in a very tight area close to the exhaust header and bike frame. The instructions that come with the kit and the videos help a lot but they mostly talk about the 500. After working for some time trying to gain access to the nut that removes the air valve I contacted BDSB and asked if there was an easier way to remove the valve or must I remove the muffler, header pipe and exhaust port. They responded promptly and confirmed that on the 350 that was the only way to get it off.

As a result, I removed the muffler, header pipe and exhaust port, all of which can be accomplished quickly except for the springs holding the header pipe into the exhaust port. I’m sure there is a tool that makes this easy but I didn’t have the tool so I had to improvise using a screw driver and awl (ice pick type of tool). I finally got the springs off but not sure how easy it will be to reinstall.

I now had access to the air valve nut and could barely reach it with a 17mm wrench. The nut loosened easily enough but the key is that the whole valve unit has to rotate to unscrew out of the engine block. Not enough room to rotate!! After trying to disassemble the valve using the Philips head screws I had basically rounded off the Philips cross in the screw heads. Now I was the one that was screwed. I then decided to drill out the screw heads using a 12” long drill bit. This worked perfectly and the screws were made of aluminum it appears. With the screws removed, the valve came apart and the part remaining in the engine block was small enough to rotate completely out of the block. I then installed the plug provided in the kit to seal up this hole.

The picture below shows the parts removed including the air valve. This really cleans up the engine plus eliminates the popping and backfires as you decelerate.

Fuel Rail

I had no idea what this was until I watched all the videos on the BDSB web page. The guys are pretty convincing so I took the hook and ordered this modification. It basically improves the fuel flow to the fuel injector by eliminating sharp bends in the plumbing on the throttle body. The only problem is that it requires digging down to the guts of the bike to get access to the throttle body. Once again, since the bike was already partially disassembled I decided now was the time to make this mod. It promises better engine performance and throttle response.

To get to the throttle body the shock is removed (already done) and the rear sub-frame is lifted by removing the bottom two bolts and loosening the top two bolts. The guy in the video and the instructions provided with the kit tells you to be a man and lift the frame with gusto but if you are a wimp, take it to a professional (funny guy). I was a bit nervous ripping my new bike apart like this but it worked and the pictures below show it in the up position. This provides adequate room to loosen the throttle body and pull it back about an inch so you can remove the old fuel plumbing and install the new connection (fuel rail) provided in the kit. This was accomplished and it went back together without much problem. The hardest part was routing the original fuel line through the frame and other components to connect to the fuel rail without putting a kink in the fuel line. I think I did that but won’t know until I get the bike back together in January and run the engine. It will be a pain to have to take it all apart to fix this if it does have a kink in the line.

Wheel Balance Weights

In a previous post I talked about how I felt this bike was dangerous over 55 mph because of the front end being almost unmanageable. The BDSB video explains why this happens and it makes sense to me so I installed their wheel weights on my bike. The cause is that the valve stem and wheel lock are on the same side of the tire to make it easier to remove the tire. What it also does is put lots of weight on one side without any counter-balance on the other side. The BDSB wheel weights are steel plates that attach to the bike spokes on the opposite side of the wheel from the valve stem and wheel lock. I won’t know if this works until I put the bike back together but anything would be an improvement.

On order:

GRUNT Mod & Snap Insert

Because I had to remove the exhaust port as part of the emissions removal kit, I decided to install the BDSB GRUNT mod. This is a machined exhaust port that improves the air flow of the exhaust gasses as they leave the engine block. I was a bit skeptical about this mod but I know that when I installed the FMF muffler and exhaust header modification on my Honda CRF 250L it turned that bike into a different animal and I rode it 3000 miles from the Atlantic Ocean to the Rocky Mountains with excellent results. Should get this mod kit in a week or so then I’ll reinstall my exhaust system.

Muffler End Cap

This mod is another improvement for the exhaust system. The original muffler end cap is very restrictive and has a detrimental impact on engine performance. The new end cap removes this restriction. The end cap mod and the GRUNT mod have a promised increase of 6-7 horse power. I assume this is for the KTM 500 EXC-F so only expect maybe 4 additional horsepower for the 350.

Additional Modifications to be accomplished when Bike is reassembled:

Throttle Position Sensor (TPS)

I purchased the TPS adjustment meter described in the video above and plan on performing this adjustment as soon as the bike is reassembled with the upgraded struts and rear shock. The TPS appears to be a critical component of engine performance and considering that I have modified the fuel flow into the throttle body (New Fuel Tank & Fuel Rail mod) and the exhaust out of the engine (GRUNT and End Cap mods) I expect this definitely needs to be addressed. I’ll provide the results of this effort in a future post.

ReKluse Auto-Clutch

Final Gearing (sprockets and chain)

I know from reading several blogs that the stock gearing for the KTM is not optimal but was selected solely to pass government noise standards (riding past a microphone at a set speed to sample noise output of the bike). My dilemma is that of the multiple forums I’ve read on this subject I get varying answers as to what the best gearing would be for my riding requirements. I changed the gearing on my Honda CRF 250L and this greatly improved the performance on both off-road and highway. It was a compromise between the two but it worked and now I have the same issue with the KTM. Here is a summary of my requirements so I welcome input from other KTM 350 riders:

1               Interstate highway riding only under extreme circumstances (never if possible) 70 mph max
2               Occasional paved secondary roads with speeds 55-65 mph
3               Primarily Gravel & Dirt Roads with speeds 35-55 mph
4               ATV & 4X4 dual track trails, some pretty rough
5               Mountain Passes including steep switch backs on slick rocks and wet trails
6               Occasional mud and sand including water crossings
7               Very little single track during day to day riding and none on the TAT
8               No radicle hill climbing

I guess to summarize, I need the KTM to be able to carry me and my gear through the Rocky Mountains and Utah Desert on 4x4 roads yet still be able to take a 2-lane highway to get to the next stretch of the TAT.

Final Comments:

I’m a firm believer that if you are going to take the road least traveled on an Adventure Bike or Dual-Sport you better know how to keep it running. As a result, I have not only the owner’s manual that came with the KTM but also the Service Manual with all the electrical schematics. This bike is so basic compared to the Yamaha Super Tenerie I rode to Alaska and the Arctic Circle and even more basic than the Honda CRF 250L on which I have ridden 3000 miles of the TAT so far. Therefore it has been a good learning experience doing the modifications listed above and I feel a lot more confident in being able to keep this bike running through the last 2400 miles of the TAT.

BTW, neither the owner’s manual nor the service manual even mention or describe the emissions system on the KTM so I have to assume they expect you to leave it alone!


  1. Glad to see you aren't afraid to take the bike apart, something that pretty much was necessary for enduro competition. Do you think you will need brush cables going from the frame to the brake and shift levers?

  2. I may add them but the TAT doesn't do much through the brush type riding. Still not a bad idea.