KTM 390 CUP BIKE

//KTM 390 CUP BIKE

KTM 390 CUP BIKE

For many riders here in the US, the long wait for the KTM 390 cup bike is over. So much to look forward to, so many expectations, so many dreams………

I had the honor of going through the M-Factory West bike at Laguna on Sunday and thanks TZ Mike for making that happen.

In all honesty the bike looks just the same other than no headlights and a superbike tail piece and after all, that is supposed to be the case between the road version and the race bike.

Was the bike the same as the press releases made us believe?

The suspension analysis was the first order of business so without hesitation we dove right in!

 

 

FORKS:

– fork preload had a range of 40 clicks and was set right in the middle at 20 clicks

– fork rebound had a range of 26 clicks and was set at 10 clicks out from max

– fork travel is 125mm, 150mm of tube exposed

– fork compression had a range of 31 clicks and was set at 10 clicks out from max

– static sag was measured at 25mm which was a huge surprise, so the top out springs are the culprit of the installed preload based on spring and spacer length combined. The forks will need to be examined to find out why this is such a big number

– the fork springs in the bike were .75nm rate

Shock:

– the rear spring is listed as 130mm long and with the bike unloaded measured 120mm, so there is 10mm of installed preload on the spring from the factory

– under its own weight, the spring collapsed another 4mm giving a total distance of 116mm

– the spring is listed as a 72nm rate

– the total static sag measurement was 15mm

– the preload collar has a 3mm set screw in it but was frozen in place so the shock needs to have the spring removed and the collar greased

– the compression adjuster had a range of 28 clicks and was set at 9 clicks from max

– the high speed adjuster is the red nut and we did not assess its range nor the current factory setting

– the rebound adjuster could not be accessed easily with the plastic hugger in place which was removed. You will need to drill a hole through this and get a long allen to be able to turn the adjuster (very hard to move)

– the adjustable ride height will be even harder to get to with the cover on.

Basic set up for suspension, no 110lb rider to measure present

Fork preload at 20 clicks

rebound at 8 clicks

compression at 6 clicks

Shock preload as is due to the frozen collar and I would have added 3 turns clockwise

compression at 1 click out

rebound at 6 clicks out

Ergonomics:

– the non-adjustable handlebars seem to be a very limiting design factor with the bars “fixed” into the upper triple clamp. This clamp must stay in place for the race season but it appears based on rules interpretation that clip-on may be allowed to accommodate taller or smaller riders and that would make a huge difference.

– the rear sets have some adjustment  so there a limited amount of range to get your feet and legs correctly situated with the bike. I’ll be able to tell right away once I ride the bike just how long an inseam the pegs will facilitate!

– having a toe pedal length adjustment is a great bonus for any rider

Brakes

– it looks like there is plenty of stopping power via the wave rotor and the big caliper but on a bike this small where momentum is everything, why so much brake power?

Mike is taking the bike to World Famous Doug Chandler for the break in at Doug’s shop in Salinas and to see how the fueling looks once break in is done. I hope to ride the bike at Sears Point April 29th although it may be possible to ride at Thunderhill on April 25th and 26th. If so I will take all my video equipment with me and see what the bike feels like as well as work up a full test plan with data for you all to review.

Sonoma Raceway First ride 4/29/15

Track temps at 109F and tires set cold at 28 rear and 30 front

Fork settings:- stock height, prerload at 10 clicks out from max, rebound at 10 clicks out, compression at 6 clicks out

Shock settings:- spring at 126mm on shock unloaded, rebound at 21 clicks out, low speed compression at 6 clicks out, high speed compression at 2 clicks out

The first ride was to see how I fit the bike more than anything else especially in regards to the fixed handlebars. I can say it took several laps to actually get my arms coordinated with the riding position in allowing my elbows to relax, bend and find the right angle to allow loose hands on the bars.

I also found that no matter what I did or how I moved around, the seat was always extremely intrusive, especially on the front edge and where the superbike tail suddenly gets a lot wider. I doubt that riders in the 5′ to 5’6″ range will experience both these physical concerns simultaneously. Besides, that may just be me being overly observant.

I will say the front forks really were excellent with the as-shipped set up of spring rate and damping. If I gradually built pressure the forks were butter smooth but if I had the lean on the brakes, the forks would accelerate through the travel. Not surprising at 210lbs fully geared up……

Yes that meant that bottom out was exactly where we guessed it would be. However, bottom out wasn’t harsh at all nor did it suddenly over stress the tire to deform the carcass or cause chatter on the edge of the tire.

The shock was way too harsh and it is far too easy to say it is too soft in this situation. With 8mm of free sag and 30mm of rider sag, I knew I needed to dial the preload and damping back to give the shock more stroke (it was only getting to 75% of the total stroke available).

Tire pressure and grip on the Rosso II tires was inspiring and I had the little bike pinned everywhere. Why pinned? Because the engine just kept pulling to red line and never fell down. That being said there’s a big spread between gears so you don’t shift much. Yes folks, as advertized it is all about corner speed with this bike!

At this point the bike was handed over to Valentine Welch who will be the rider for M Factory West.com in the Moto America series. Valentine is no stranger to racing and in the last 18 months has made high profile strides to the front of the pack in 250 Superbike and now is establishing herself in the 450 Superbike grid with a GSXR450 triple.

The suspension was reset for her 120lb weight but to get the rider sag we were looking for, the rear shock free sag had to increase to an unacceptable 30mm. Rule of thumb is large free sag and low rider sag = spring is too stiff and corrrect rider sag and no free sag = spring is too soft. So, owner Mike Studzinski has the spring on order from HMC. The net result was that the bike “floated” in her words – very precise due to all the free sag – so the bike never had any grip and worse, had massive weight transfer from braking and acceleration.

I’m hoping that the lighter springs will be light enough and if not, Mike will have to get some custom springs made. That would be very problematic when the bike appears to be pitched at young riders between 80-130lbs (or did I not get the marketing memo?).

By | 2018-01-27T19:00:15+00:00 January 4th, 2018|Categories: Reviews|0 Comments

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Journalist, published author, 1-1 coach and mentor, video presenter

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